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    M. Chakraverty, H.M. Kittur & P.A. Kumar First Principle Simulations of Various Magnetic Tunnel Junctions for Applications in Magnetoresistive Random Access Memories 2013 Nanotechnology, IEEE Transactions on
    Vol. 12(6)Nanotechnology, IEEE Transactions on, 971-977 
    DOI  
    Abstract: This paper reports the first principle simulations of Fe/MgO/Fe, Fe/Y2O3/Fe, Fe/HfO2/Fe, and Fe/Al2O3/Fe magnetic tunnel junctions (MTJs). From the device-level and circuit-level simulations carried out in this paper, the Fe/MgO/Fe configuration has been found to be the best. From the device-level simulations, all the four configurations of MTJs have been compared with regards to the bias dependence of tunnel magnetoresistance ratios (TMRs), insulator thickness dependence of TMR, and insulator thickness dependence of parallel and antiparallel state resistances. Finally, from the circuit-level simulations, the static and switching power dissipations have been computed along with the delay time estimation.
    Keywords: ATK, Application, hafnium compounds, iron, magnesium compounds, random-access storage, yttrium compounds, Fe-Al2O3-Fe, Fe-HfO2-Fe, Fe-MgO-Fe, Fe-Y2O3-Fe, antiparallel state resistances, circuit-level simulations, device-level simulations, insulator thickness dependence, magnetic tunnel junctions, magnetoresistive random access memories, tunnel magnetoresistance ratios, Atomic layer deposition, Insulators, Iron, Magnetic separation, Magnetic tunneling, Resistance, Tunneling magnetoresistance, Density functional theory (DFT), MRAM, local spin density approximation (LSDA), magnetic tunnel junction (MTJ)
    Area: nvm; interfaces; semi; spin
    BibTeX:
    @article{Chakraverty2013a,
      author = {Chakraverty, M. and Kittur, H.M. and Kumar, P.A.},
      title = {First Principle Simulations of Various Magnetic Tunnel Junctions for Applications in Magnetoresistive Random Access Memories},
      booktitle = {Nanotechnology, IEEE Transactions on},
      journal = {Nanotechnology, IEEE Transactions on},
      year = {2013},
      volume = {12},
      number = {6},
      pages = {971--977},
      doi = {http://dx.doi.org/10.1109/TNANO.2013.2274902}
    }
    
    Michiharu Tabe, Daniel Moraru, Earfan Hamid, Arup Samanta, Le The Anh, Takeshi Mizuno & Hiroshi Mizuta Dopant-Atom-Based Tunnel SOI-MOSFETs 2013 ECS Transactions
    Vol. 58(9), 89-95 
    DOI  
    Abstract: Recently, the role of dopants in Si devices has been changing after a long and successful history in Si integrated circuit technology. The change can be seen as a transition from "bulk-type" dopants, with averaged potential, to "atom-type" dopants, with individual atomistic potential. Furthermore, dopant energy levels are modified by the effect of dielectric misfit with surrounding Si and the outside structure, which leads to the transformation of conventional dopants into artificial deep dopants. This effect may be significantly important for the purpose of the extension of operation temperature range of dopant-atom devices from low temperatures (<50 K) to room temperature.
    Keywords: ATK; Application; silicon nanostructures; single donor; spectroscopy; transistor; channel; devices; donors; doping
    Area: semi
    BibTeX:
    @article{Tabe2013,
      author = {Tabe, Michiharu and Moraru, Daniel and Hamid, Earfan and Samanta, Arup and Anh, Le The and Mizuno, Takeshi and Mizuta, Hiroshi},
      title = {Dopant-Atom-Based Tunnel SOI-MOSFETs},
      journal = {ECS Transactions},
      year = {2013},
      volume = {58},
      number = {9},
      pages = {89--95},
      doi = {http://dx.doi.org/10.1149/05809.0089ecst}
    }
    
    Qiu-Hua Wu, Peng Zhao & De-Sheng Liu First-Principles Study of the Rectifying Properties of the Alkali-Metal-Atom-Doped BDC60 Molecule 2014 Acta Physico-Chimica Sinica
    Vol. 30(1), 53 
    DOI URL 
    Abstract: We investigated the effect of alkali-metal-atom doping on the electronic transport properties of BDC60 molecules, using a combination of first-principles density-functional theory and the non-equilibrium Green's function. Our calculation results show that alkali-metal-atom-doped BDC60 molecules exhibit good rectifying and negative differential resistance behaviors at very low bias. The intrinsic mechanisms for these phenomena are discussed systematically in terms of the transmission spectra and frontier molecular orbitals, as well as their spatial distributions under various external applied biases. Our study will help in developing future applications of BDC60 molecules in low-bias rectifying and negative differential resistance molecular devices.
    Keywords: ATK; Application; density functional theory; non-equilibrium Green's function; rectifying; negative differential resistance (NDR); electronic transport; negative differential resistance; single-C-60 transistor; transport-properties; diodes; C-60; rectification; encapsulation; rectifiers; nitrogen
    Area: molecular electronics; fullerenes
    BibTeX:
    @article{WUQiu-Hua2014,
      author = {Wu, Qiu-Hua and Zhao, Peng and Liu, De-Sheng},
      title = {First-Principles Study of the Rectifying Properties of the Alkali-Metal-Atom-Doped BDC60 Molecule},
      journal = {Acta Physico-Chimica Sinica},
      publisher = {Acta Phys. Chim. Sin.},
      year = {2014},
      volume = {30},
      number = {1},
      pages = {53},
      url = {http://www.whxb.pku.edu.cn/EN/abstract/article_28621.shtml},
      doi = {http://dx.doi.org/10.3866/PKU.WHXB201311081}
    }
    
    Zhi Yang, Baolong Zhang, Xuguang Liu, Xiuyan Li, Yongzhen Yang, Shijie Xiong & Bingshe Xu Size-dependent magnetic order and giant magnetoresistance in organic titanium-benzene multidecker cluster 2014 Phys. Chem. Chem. Phys.
    Vol. 16(5), 1902-1908 
    DOI  
    Abstract: Using density functional theory and non-equilibrium Green's function method, we investigated the magnetic and transport properties of small organic titanium-benzene sandwich clusters TinBzn+1 (n = 1-3). The results show that TiBz2 is nonmagnetic while Ti2Bz3 and Ti3Bz4 are ferromagnetic, and our prediction is in agreement with experimental observation. The double exchange mechanism plays a key role in the ferromagnetism of larger clusters. With Ni as the two electrodes, significant spin-filter efficiency (SFE) and giant magnetoresistance (GMR) were found in the TinBzn+1 molecular junction. These transport properties could be controlled by cluster size, bias voltage or gate voltage. Specially, a sign-reversible GMR effect was observed in the Ti2Bz3 molecular junction. Finally, the microscopic mechanisms of SFE and GMR were suggested.
    Keywords: ATK; Application; molecular electronics; rice-ball structures; sandwich clusters; transition-metals; decker-sandwich; gas-phase; complexes; spintronics
    Area: molecular electronics
    BibTeX:
    @article{Yang2014,
      author = {Yang, Zhi and Zhang, Baolong and Liu, Xuguang and Li, Xiuyan and Yang, Yongzhen and Xiong, Shijie and Xu, Bingshe},
      title = {Size-dependent magnetic order and giant magnetoresistance in organic titanium-benzene multidecker cluster},
      journal = {Phys. Chem. Chem. Phys.},
      publisher = {The Royal Society of Chemistry},
      year = {2014},
      volume = {16},
      number = {5},
      pages = {1902--1908},
      doi = {http://dx.doi.org/10.1039/C3CP54352H}
    }
    
    Yukihito Matsuura Tunnel current across linear homocatenated germanium chains 2014 Journal of Applied Physics
    Vol. 115(4), 043701 
    DOI  
    Abstract: The electronic transport properties of germanium oligomers catenating into linear chains (linear Ge chains) have been theoretically studied using first principle methods. The conduction mechanism of a Ge chain sandwiched between gold electrodes was analyzed based on the density of states and the eigenstates of the molecule in a two-probe environment. Like that of silicon chains (Si chains), the highest occupied molecular orbital of Ge chains contains the extended sigma-conjugation of Ge 4p orbitals at energy levels close to the Fermi level; this is in contrast to the electronic properties of linear carbon chains. Furthermore, the conductance of a Ge chain is expected to decrease exponentially with molecular length L. The decay constant beta, which is defined as exp(-beta*L), of a Ge chain is similar to that of a Si chain, whereas the conductance of the Ge chains is higher than that of Si chains even though the Ge-Ge bond length is longer than the Si-Si bond length.
    Keywords: ATK; Application; molecular electronics; elemental semiconductors; atomic chain
    Area: molecular electronics; semi; nanowire
    BibTeX:
    @article{Matsuura2014,
      author = {Matsuura, Yukihito},
      title = {Tunnel current across linear homocatenated germanium chains},
      journal = {Journal of Applied Physics},
      year = {2014},
      volume = {115},
      number = {4},
      pages = {043701},
      doi = {http://dx.doi.org/10.1063/1.4863118}
    }
    
    Jing Zeng & Ke-Qiu Chen Magnetic configuration dependence of magnetoresistance in a Fe-porphyrin-like carbon nanotube spintronic device 2014 Applied Physics Letters
    Vol. 104(3), 033104 
    DOI  
    Abstract: By using nonequilibrium Green's functions in combination with the density functional theory, we investigate the spin-dependent transport properties in a Fe-porphyrin-like carbon nanotube spintronic device. The results show that magnetoresistance ratio is strongly dependent on the magnetic configuration of the Fe-porphyrin-like carbon nanotube. Under the application of the external magnetic field, the magnetoresistance ratio of the device can be increased from about 19% to about 1020% by tuning the magnetic configuration in the device. Our results confirm that the magnetic configuration is a key factor for obtaining a high-performance spintronic device.
    Keywords: ATK; Application; molecular electronics; nanotubes; spintronics
    Area: molecular electronics; nanotubes; spin
    BibTeX:
    @article{Zeng2014,
      author = {Zeng, Jing and Chen, Ke-Qiu},
      title = {Magnetic configuration dependence of magnetoresistance in a Fe-porphyrin-like carbon nanotube spintronic device},
      journal = {Applied Physics Letters},
      year = {2014},
      volume = {104},
      number = {3},
      pages = {033104},
      doi = {http://dx.doi.org/10.1063/1.4862895}
    }
    
    N.N. Rusyaev & S.V. Spiridonov Nanowires defects, investigation of opportunity of early detection 2013 Vestnik Moskovskogo aviatsionnogo instituta
    Vol. 20(3) 
    URL 
    Abstract: This paper is devoted to investigation of possibility of defect detection in nanoconductors based on their transport property changes. The detection of nanodefects is a significant challenge, because it requires studying each individual sample along all stages of the engineering process. For effective checkout of the produced devices parameters there is a need for more fast, simple, and productive means for the defect detection. In this paper we investigate the possibility of detecting nanodefects according to their manifestation in the transport properties of a conductor. One of the possible types of such defects is the «conductor-defect-conductor» transition where the defect represents a suspended one- dimensional chain of atoms. The reason for studying defects of this type is rather high probability of emergence of such defects during operation under the mechanical or thermal impacts, and the possibility of occurrence of such defects in various manufacturing processes.

    The investigation was performed by mathematical modeling under Atomistix Virtual Nano Lab software. For the calculations we used two theoretical methods: EHT (Extended Huckel) and the method of Classic Potential. Based on these methods the models of defect-free and defective conductors were developed.

    The defect in these models was considered as an approximation to the model of a partial break of a conductor. The parameters for the comparative analysis included following characteristics: the difference of electron density, the difference of electrostatic potentials, molecular spectra, current-voltage curves. The measurements were performed on the two-electrode scheme with external voltage varying in the range from -2 to 2 V. Comparative analysis of the electronic structures and transport properties showed that there were differences sufficient enough for defect detection based on current-voltage characteristic changes.

    Nevertheless, it is necessary to keep in mind that we have investigated only one type of such nanodefects. In our case the defect conductive chain was considered to be perpendicular to main conductor side, and to have only methods for studying other types of defects.

    Keywords: ATK-SE; Application; nanowire; defects detection; conductors; transport properties; sensor
    Area: nanowires
    BibTeX:
    @article{Rusyaev2013,
      author = {Rusyaev, N. N. and Spiridonov, S. V.},
      title = {Nanowires defects, investigation of opportunity of early detection},
      journal = {Vestnik Moskovskogo aviatsionnogo instituta},
      year = {2013},
      volume = {20},
      number = {3},
      url = {http://www.mai.ru/science/vestnik/eng/publications.php?ID=44109&eng=Y}
    }
    
    Jichen Dong, Hui Li & Li Li Multi-functional nano-electronics constructed using boron phosphide and silicon carbide nanoribbons 2013 NPG Asia Mater
    Vol. 5, e56 
    DOI  
    Abstract: First-principles density functional theory and non-equilibrium Green function calculations provide theoretical support for the promising applications of multi-functional nano-electronics constructed using zigzag boron phosphide (BP) nanoribbons (zBPNRs) and silicon carbide nanoribbons (zSiCNRs). The results indicate that zBPNRs are non-magnetic direct bandgap semiconductors with bandgaps of ~1 eV. Devices constructed using hybrid zSiC-BP-SiC nanoribbon structures are found to exhibit not only significant field-effect characteristics but also tunable negative differential resistance. Moreover, Y- and Delta-shaped nano-structures composed of zBPNRs and zSiCNRs exhibit pronounced spin polarization properties at their edges, suggesting their potential use in spintronic applications. Interestingly, a transverse electric field can convert zBPNRs to non-magnetic indirect bandgap semiconductors, ferrimagnetic semiconductors or half-metals depending on the strength and direction of the field. This study may provide a new path for the exploration of nano-electronics.
    Keywords: ATK, Application, BP nanoribbons, density functional theory, hybrid structure, multi-functional nano-electronics, non-equilibrium Green Function, SiC nanoribbons
    Area: molecular electronics; hexflats
    BibTeX:
    @article{Dong2013a,
      author = {Dong, Jichen and Li, Hui and Li, Li},
      title = {Multi-functional nano-electronics constructed using boron phosphide and silicon carbide nanoribbons},
      journal = {NPG Asia Mater},
      publisher = {Nature Japan KK},
      year = {2013},
      volume = {5},
      pages = {e56},
      doi = {http://dx.doi.org/10.1038/am.2013.31}
    }
    
    S. Sivasathya & D. John Thiruvadigal Ab Initio Study of Electron Transport Properties in Single Wall Carbon Nanotubes Connected with Different Metallic Electrodes 2013 Journal of Computational and Theoretical Nanoscience
    Vol. 10(10), 2391-2397 
    DOI  
    Abstract: We report the transport behaviour and evaluate the contact resistance on electrical conductance of an open-end metallic single wall carbon nanotube with and without local structural defects connected with metal interfaces like Copper (Cu), Gold (Au) and Silver (Ag) using the non-equilibrium Green's functions approach together with the density functional theory (DFT). The transmission spectra and the projected density of states for the devices such as Cu-CNT-Cu, Au-CNT-Au and Ag-CNT-Ag are compared with and without inclusion of defects. Ag-CNT-Ag has been observed to possess the maximum electron transport. We found that the Stone-Wales defect has almost negligible impact on the electrical performance compared to the monovacancy defect of single wall carbon nanotube (3, 3) and its junction with the metal electrodes at the Fermilevel. The Current-Voltage (I-V) characteristics of the devices are studied using the generalized Landauer-Buttiker formalism, from which the contact resistance is determined under low bias condition. Our results indicate that the contact resistance between the metal electrodes and a single wall carbon nanotube decreases in the order given by Cu > Au > Ag interfaces.
    Keywords: ATK, Application, contact resistance, density functional theory, I-V characteristics, monovacany, single wall carbon nanotube, Stone-Wales defects, transport properties, quantum-mechanics, defects, conductance
    Area: nanotubes
    BibTeX:
    @article{Sivasathya2013a,
      author = {Sivasathya, S. and Thiruvadigal, D. John},
      title = {Ab Initio Study of Electron Transport Properties in Single Wall Carbon Nanotubes Connected with Different Metallic Electrodes},
      journal = {Journal of Computational and Theoretical Nanoscience},
      year = {2013},
      volume = {10},
      number = {10},
      pages = {2391--2397},
      doi = {http://dx.doi.org/10.1166/jctn.2013.3220}
    }
    
    K.I. Doig, F. Aguesse, A.K. Axelsson, N.M. Alford, S. Nawaz, V.R. Palkar, S.P.P. Jones, R.D. Johnson, R.A. Synowicki & J. Lloyd-Hughes Coherent magnon and acoustic phonon dynamics in tetragonal and rare-earth-doped BiFeO3 multiferroic thin films 2013 Phys. Rev. B
    Vol. 88(9), 094425 
    DOI  
    Abstract: Coherent magnons and acoustic phonons were impulsively excited and probed in thin films of the room temperature multiferroic Bi(1-x-y)Dy(x)La(y)FeO3 using femtosecond laser pulses. The elastic moduli of rhombohedral, tetragonal, and rare-earth doped BiFeO3 were determined from acoustic-mode frequencies in conjunction with spectroscopic ellipsometry. A weak ferromagnetic order, induced alternately by magnetization in the growth direction or by tetragonality, created a magnon oscillation at 75 GHz, indicative of a Dzyaloshinskii-Moriya interaction energy of 0.31 meV.
    Keywords: ATK, Application, experimental comparison
    Area: dft
    BibTeX:
    @article{Doig2013,
      author = {Doig, K. I. and Aguesse, F. and Axelsson, A. K. and Alford, N. M. and Nawaz, S. and Palkar, V. R. and Jones, S. P. P. and Johnson, R. D. and Synowicki, R. A. and Lloyd-Hughes, J.},
      title = {Coherent magnon and acoustic phonon dynamics in tetragonal and rare-earth-doped BiFeO3 multiferroic thin films},
      journal = {Phys. Rev. B},
      publisher = {American Physical Society},
      year = {2013},
      volume = {88},
      number = {9},
      pages = {094425},
      doi = {http://dx.doi.org/10.1103/PhysRevB.88.094425}
    }
    
    Wu Qiu-Hua, Zhao Peng & Liu De-Sheng Low Bias Negative Differential Resistance Behavior in Carbon/Boron Nitride Nanotube Heterostructures 2013 Chinese Physics Letters
    Vol. 30(10), 107304- 
    DOI  
    Abstract: Based on the non-equilibrium Green's method and density functional theory, we investigate the electronic transport properties of ternary heterostructures based on carbon nanotubes and boron nitride nanotubes, with different atomic compositions, coupled to gold electrodes. Negative differential resistance (NDR) behavior can be observed due to suppression of the conduction channel at a certain bias. More importantly, the position of NDR can be tuned into the bias range as low as tens of meV by increasing the length of boron nitride nanotube. The peak-to-valley ratio, which is a typical character of NDR behavior, is also sensitive to the atomic compositions.
    Keywords: ATK, Application, carbon nanotube, boron-nitride, heterostructure, negative differential resistance (NDR)
    Area: nanotubes
    BibTeX:
    @article{Qiu-Hua2013,
      author = {Qiu-Hua, Wu and Peng, Zhao and De-Sheng, Liu},
      title = {Low Bias Negative Differential Resistance Behavior in Carbon/Boron Nitride Nanotube Heterostructures},
      journal = {Chinese Physics Letters},
      year = {2013},
      volume = {30},
      number = {10},
      pages = {107304--},
      doi = {http://dx.doi.org/10.1088/0256-307X/30/10/107304}
    }
    
    Yuta Tsuji, Junya Koga & Kazunari Yoshizawa Asymmetric Diarylethene as a Dual-Functional Device Combining Switch and Diode: 2013 Bulletin of the Chemical Society of Japan
    Vol. 86(8), 947-954 
    DOI  
    Abstract: Diarylethenes are photosensitive pi-conjugated molecules, being of great promise in potential applications to various molecular devices. Although the switching properties of diarylethenes have been widely investigated experimentally and theoretically, little is known about their rectifying diode-like behavior. In this study, electron-transport properties of asymmetric diarylethenes incorporating two different heterocyclic five-membered rings with opposite electronic demands are investigated with the nonequilibrium Green function combined with density functional theory. The aim of this study is to derive the effect of the heteroatomic defects on not only switching but also rectifying characteristics of the asymmetric diarylethenes. Obtained results show that a silicon atom involved in the diarylethenes plays an important role in the current rectifying as well as switching performance. It is found that maximum rectification ratios of the asymmetric diarylethenes increase linearly with an increase in electronegativity difference between the asymmetrically arranged heteroatoms. The silicon- and oxygen-containing asymmetric diarylethene is suggested to be a good potential candidate for a novel molecular electronic device combining a switch and a diode.
    Keywords: ATK, Application, molecular electronics, rectification, defect
    Area: molecular electronics
    BibTeX:
    @article{Tsuji2013a,
      author = {Tsuji, Yuta and Koga, Junya and Yoshizawa, Kazunari},
      title = {Asymmetric Diarylethene as a Dual-Functional Device Combining Switch and Diode: },
      journal = {Bulletin of the Chemical Society of Japan},
      year = {2013},
      volume = {86},
      number = {8},
      pages = {947--954},
      doi = {http://dx.doi.org/10.1246/bcsj.20130089}
    }
    
    J.C. Dong, H. Li, F.W. Sun, K. Zhang & Y.F. Li Theoretical Study of the Properties of Si Nanowire Electronic Devices 2011 J. Phys. Chem. C
    Vol. 115(28)The Journal of Physical Chemistry C, 13901-13906 
    DOI  
    Abstract: Electron-transport properties of three terminal field-effect devices based on both pure and doped Si nanowires with diameters less than 1 nm are theoretically studied. The results indicate that some devices possess electronic functions, such as current amplification and robust negative differential resistance accompanied with large on-off ratios. Three kinds of mechanisms are proposed to interpret different negative differential resistance phenomena of some devices investigated in this paper. Not only structures of nanowires but also applied bias can change the mechanism of negative differential resistance. Furthermore, the performance of these devices is mainly dependent on the doping and atomic arrangement of Si nanowires. This work provides a deep insight into the electron-transport properties of functional electronic nanodevices.
    Keywords: ATK, Application, nanowire, field-effect transistor, doping
    Area: nanowires
    BibTeX:
    @article{Dong2011,
      author = {Dong, J. C. and Li, H. and Sun, F. W. and Zhang, K. and Li, Y. F.},
      title = {Theoretical Study of the Properties of Si Nanowire Electronic Devices},
      booktitle = {The Journal of Physical Chemistry C},
      journal = {J. Phys. Chem. C},
      publisher = {American Chemical Society},
      year = {2011},
      volume = {115},
      number = {28},
      pages = {13901--13906},
      doi = {http://dx.doi.org/10.1021/jp2007045}
    }
    
    Satoshi Kaneko, Jinjiang Zhang, Jianwei Zhao & Manabu Kiguchi Electronic Conductance of Platinum Atomic Contact in a Nitrogen Atmosphere 2013 J. Phys. Chem. C
    Vol. 117(19)The Journal of Physical Chemistry C, 9903-9907 
    DOI  
    Abstract: We have investigated the platinum atomic contact in a nitrogen atmosphere using mechanically controllable break junction technique and theoretical calculation. Conductance, dI/dV measurement, and theoretical calculation revealed a single N2 molecule placed between platinum electrodes, where the N2 molecular axis was parallel to the junction axis. The conductance of the single N2 molecular junction was 1 G0 (=2e2/h), which was comparable to that of metal atomic contacts indicating the strong interaction between the nitrogen molecule and Pt electrodes. Theoretical calculation supported the high conductivity of the molecular junction and revealed that two dominant channels contributed to the electron transport through the junction. The two dominant channels were from the coupling between orbitals (dxz and dyz) of Pt atom and orbitals (px and py) of N atom.
    Keywords: ATK, Application, atomic contact, molecular electronics, break junction
    Area: molecular electronics
    BibTeX:
    @article{Kaneko2013,
      author = {Kaneko, Satoshi and Zhang, Jinjiang and Zhao, Jianwei and Kiguchi, Manabu},
      title = {Electronic Conductance of Platinum Atomic Contact in a Nitrogen Atmosphere},
      booktitle = {The Journal of Physical Chemistry C},
      journal = {J. Phys. Chem. C},
      publisher = {American Chemical Society},
      year = {2013},
      volume = {117},
      number = {19},
      pages = {9903--9907},
      doi = {http://dx.doi.org/10.1021/jp401562d}
    }
    
    Muhammed Ihab Schukfeh, Kristian Storm, Ahmed Mahmoud, Roar R. Søndergaard, Anna Szwajca, Allan Hansen, Peter Hinze, Thomas Weimann, Sofia Fahlvik Svensson, Achyut Bora, Kimberly A. Dick, Claes Thelander, Frederik C. Krebs, Paolo Lugli, Lars Samuelson & Marc Tornow Conductance Enhancement of InAs/InP Heterostructure Nanowires by Surface Functionalization with Oligo(phenylene vinylene)s 2013 ACS Nano
    Vol. 7(5)ACS Nano, 4111-4118 
    DOI  
    Abstract: We have investigated the electronic transport through 3 micrometer long, 45 nm diameter InAs nanowires comprising a 5 nm long InP segment as electronic barrier. After assembly of 12 nm long oligo(phenylene vinylene) derivative molecules onto these InAs/InP nanowires, we observed a pronounced, nonlinear I-V characteristic with significantly increased currents of up to 1 microA at 1 V bias, for a back-gate voltage of 3 V. As supported by our model calculations based on a nonequilibrium Green Function approach, we attribute this effect to charge transport through those surface-bound molecules, which electrically bridge both InAs regions across the embedded InP barrier.
    Keywords: ATK; Application; molecular electronics; nanowire; experimental comparison
    Area: molecular electronics; nanowires
    BibTeX:
    @article{Schukfeh2013,
      author = {Schukfeh, Muhammed Ihab and Storm, Kristian and Mahmoud, Ahmed and Søndergaard, Roar R. and Szwajca, Anna and Hansen, Allan and Hinze, Peter and Weimann, Thomas and Svensson, Sofia Fahlvik and Bora, Achyut and Dick, Kimberly A. and Thelander, Claes and Krebs, Frederik C. and Lugli, Paolo and Samuelson, Lars and Tornow, Marc},
      title = {Conductance Enhancement of InAs/InP Heterostructure Nanowires by Surface Functionalization with Oligo(phenylene vinylene)s},
      booktitle = {ACS Nano},
      journal = {ACS Nano},
      publisher = {American Chemical Society},
      year = {2013},
      volume = {7},
      number = {5},
      pages = {4111--4118},
      doi = {http://dx.doi.org/10.1021/nn400380g}
    }
    
    Xi-Feng Shi, Na Li, Ke Zhao, Guan-Wei Cui, Ying-Qiang Zhao, Ming-Yue Ma, Ke-Hua Xu, Ping Li, Yu-Bin Dong & Bo Tang A dye-sensitized FeOOH-CNT photocatalyst with three electron transfer channels regulated by hydrogen bonding 2013 Applied Catalysis B: Environmental
    Vol. 136-137(0), 334-340 
    DOI  
    Abstract: A dye-sensitized photocatalyst with three electron transfer channels was constructed, in which FeOOH and photosensitizer RuL2Cl2·2H2O were employed as the electron donor, carbon nanotubes were served as the electron container. The catalytic activities of the photocatalyst were evaluated by a model photocatalytic carboxylation reaction of phenol by CO2. The photocatalytic efficiency and transient photocurrent density increased obviously when the catalysis reaction was carried out in cyclohexane compared to two electron activations in water, which suggested the formation of three electron transfer channels in the catalytic system. Moreover, time-dependent density functional theory (TD-DFT) calculation results also indicated the existence of three electron transfer channels assisted by intermolecular hydrogen bonding interaction.
    Keywords: ATK, Application, photocatalysis, electron transfer, three channels, hydrogen bonding, nanotube
    Area: nanotubes
    BibTeX:
    @article{Shi2013,
      author = {Shi, Xi-Feng and Li, Na and Zhao, Ke and Cui, Guan-Wei and Zhao, Ying-Qiang and Ma, Ming-Yue and Xu, Ke-Hua and Li, Ping and Dong, Yu-Bin and Tang, Bo},
      title = {A dye-sensitized FeOOH-CNT photocatalyst with three electron transfer channels regulated by hydrogen bonding},
      journal = {Applied Catalysis B: Environmental},
      year = {2013},
      volume = {136-137},
      number = {0},
      pages = {334--340},
      doi = {http://dx.doi.org/10.1016/j.apcatb.2013.02.005}
    }
    
    Yuta Tsuji & Kazunari Yoshizawa Current Rectification through pi-pi Stacking in Multilayered Donor-Acceptor Cyclophanes 2012 J. Phys. Chem. C
    Vol. 116(50)The Journal of Physical Chemistry C, 26625-26635 
    DOI  
    Abstract: Extended pi-stacked molecules have attracted much attention since they play an essential role in both electronic devices and biological systems. In this article electron transport properties of a series of multilayered cyclophanes with the hydroquinone donor and quinone acceptor units in the external positions are theoretically studied with applications to molecular rectifiers in mind. Calculations of electron transport through the pi-pi stacked structures in the multilayered cyclophanes are performed by using nonequilibrium Green's function method combined with density functional theory. Calculated transmission spectra show that the conductance decreases exponentially with the length of the molecule with a decay factor of 0.75 Å^-1, which lies for the values between pi-conjugated molecules and sigma-bonded molecules. Applied bias calculations provide current-voltage curves, which exhibit good rectifying behavior. The rectification mechanism in the coherent transport regime is qualitatively explained by the response of the frontier orbital energy levels, especially LUMO levels, to the applied bias, where the rectifying direction is expected to be opposite to the Aviram-Ratner model. The maximum value of rectification ratio increases with an increase in the number of stacking layers due to the effective separation of the donor and acceptor parts, where effects from the opposite electrodes to the donor and acceptor are negligible. Multilayered donor-acceptor cyclophanes are suitable materials for investigating the relationship among electron transport properties, rectification properties, and molecular length (separation between the donor and acceptor parts).
    Keywords: ATK; Application; molecular electronics; rectification
    Area: molecular electronics
    BibTeX:
    @article{Tsuji2012b,
      author = {Tsuji, Yuta and Yoshizawa, Kazunari},
      title = {Current Rectification through pi-pi Stacking in Multilayered Donor-Acceptor Cyclophanes},
      booktitle = {The Journal of Physical Chemistry C},
      journal = {J. Phys. Chem. C},
      publisher = {American Chemical Society},
      year = {2012},
      volume = {116},
      number = {50},
      pages = {26625--26635},
      doi = {http://dx.doi.org/10.1021/jp308849t}
    }
    
    Y. Min, J.H. Fang, C.G. Zhong, Z.C. Dong, C.P. Chen & K.L. Yao Localization of the energy states of lead inducing the effect of rectification and negative differential resistance predicted by first-principles study 2013 Int. J. Mod. Phys. B
    Vol. 27(17)International Journal of Modern Physics B, 1350081 
    DOI  
    Abstract: The first-principles calculations of the transport characteristics of 4-(5-(2-(5-(4-mercaptophenyl)thiophene-2-yl)ethyl)pyridin-2-yl)benzenethiol sandwiched between two gold leads are performed. The effect of rectification and negative differential resistance (NDR) are obtained, which promise the potential applications in the field of molecular electronics. The rectification effect is 4.49. The peak/valley ratio of the NDR effect is as large as 4.51 for the forward bias and 12.09 for the reverse bias. The strong coupling between gold lead and molecule through thiolate results in the localization of the energy states of gold lead, which may induce the effect of rectification and NDR.
    Keywords: ATK; Application; molecular electronics; density functional theory; nonequilibrium Green's function; electrons transport; LDOS
    Area: molecular electronics
    BibTeX:
    @article{Min2013a,
      author = {Min, Y. and Fang, J. H. and Zhong, C. G. and Dong, Z. C. and Chen, C. P. and Yao, K. L.},
      title = {Localization of the energy states of lead inducing the effect of rectification and negative differential resistance predicted by first-principles study},
      booktitle = {International Journal of Modern Physics B},
      journal = {Int. J. Mod. Phys. B},
      publisher = {World Scientific Publishing Co.},
      year = {2013},
      volume = {27},
      number = {17},
      pages = {1350081},
      doi = {http://dx.doi.org/10.1142/S0217979213500811}
    }
    
    Bin Cui, Yuqing Xu, Guomin Ji, Hui Wang, Wenkai Zhao, Yaxin Zhai, Dongmei Li & Desheng Liu A single-molecule diode with significant rectification and negative differential resistance behavior 2014 Organic Electronics
    Vol. 15(2), 484-490 
    DOI  
    Abstract: A series of ferrocenylalkanethiol (HSCnFc) single molecular junctions are modeled and their rectification ratios (RRs) are up to 100 (for HSC11Fc), which agrees with the experiments of Whitesides et al. Not only explanation to the origin of the remarkable large RR is given, but also the reason why one order deviation of RR between HSC11Fc and HSC9Fc is discussed and depicted, which was not pointed out by previous researchers. The single asymmetric accessible molecular orbital (MO) model is evaluated, which is different from the Donor (D)-Acceptor (A) models reported before and a clear negative differential resistance (NDR) behavior is found and explained in the HSC11Fc based device.
    Keywords: ATK, Application, non-equilibrium Green's function, unimolecular diode, gate modulation, rectification, experimental comparison, doping
    Area: molecular electronics
    BibTeX:
    @article{Cui2014,
      author = {Cui, Bin and Xu, Yuqing and Ji, Guomin and Wang, Hui and Zhao, Wenkai and Zhai, Yaxin and Li, Dongmei and Liu, Desheng},
      title = {A single-molecule diode with significant rectification and negative differential resistance behavior},
      journal = {Organic Electronics},
      year = {2014},
      volume = {15},
      number = {2},
      pages = {484--490},
      doi = {http://dx.doi.org/10.1016/j.orgel.2013.11.039}
    }
    
    Milanpreet Kaur, Ravinder Singh Sawhney & Harsimran Kaur Anatomizing electronic transport through saturated alkane molecule with disparate terminal elements 2012 J. Multiscale Modelling
    Vol. 044(03)Journal of Multiscale Modelling, 1250011 
    DOI  
    Abstract: In this paper, we anatomized transport properties of butane belonging to the saturated alkane group (CnH2n+2) using three terminal anchor elements (nitrogen, oxygen and sulfur) in Trans configuration connected to gold electrodes, forming a two probe model. The transport properties of three variants of butane were investigated in terms of Transmission spectra, Eigenstates, I-V characteristics and differential conductance for different values of biasing voltage using Keldysh's non-equilibrium Green's function combined with semi-empirical extended Hückel theory. Amongst the three binding elements, Butane exhibited maximum charge transfer with sulfur, then with nitrogen and least with oxygen. The HOMO-LUMO gap for both nitrogen and Oxygen as terminal anchoring elements suggested that conduction was virtually impossible through Butane in particular cases. Nature of Ballistic current for butane anchored with sulfur is ideal for its applicability as nano-diode or resonant tunneling diodes (RTDs) in arena of quantum-electronics due to its strong coupling between the terminal atoms and carbon atoms of butane. The retrenching order obtained in terms of conductance is S > N > O anchored butane molecule which seemed in full confirmation with the results of Transmission spectrum and its Eigenstates and proved sulfur to be a promising binding element and can produce much better results in comparison to oxygen and nitrogen. This paper marked another step in the field of molecular electronics as the butane anchored with sulfur has characteristics in conjunction to the semiconductor junction diode.
    Keywords: ATK; Application; molecular electronics; extended Hückel theory (EHT); non-equilibrium Green's function (NEGF); butane (C4H10); highest occupied molecular orbital (HOMO); Lowest unoccupied molecular orbital (LUMO)
    Area: molecular electronics
    BibTeX:
    @article{Kaur2012,
      author = {Kaur, Milanpreet and Sawhney, Ravinder Singh and Kaur, Harsimran},
      title = {Anatomizing electronic transport through saturated alkane molecule with disparate terminal elements},
      booktitle = {Journal of Multiscale Modelling},
      journal = {J. Multiscale Modelling},
      publisher = {World Scientific Publishing Co.},
      year = {2012},
      volume = {044},
      number = {03},
      pages = {1250011},
      doi = {http://dx.doi.org/10.1142/S1756973712500114}
    }
    
    H.J. Liu Thermoelectric Properties of Carbon Nanotubes and Related One-Dimensional Structures 2014
    Vol. 16Lecture Notes in Nanoscale Science and Technology, 363-391 
    DOI  
    Abstract: Using nonequilibrium molecular dynamics simulations and nonequilibrium Green's function method, we investigate the thermoelectric properties of carbon nanotubes and related one-dimensional structures, which include ultrasmall and larger diameter carbon nanotubes, as well as graphene nanoribbons (GNRs) and carbon nanowires (CNWs). It is found that the transmission function of these one-dimensional carbon nanostructures display a clear stepwise structure that gives the number of electron channels. By optimizing the carrier concentration, characteristic size, and/or operating temperature, these systems could exhibit very high figure of merit. Moreover, their thermoelectric performance can be significantly enhanced via man approaches such as surface design, isotope substitution, isoelectronic impurities, and hydrogen adsorption. It is thus reasonable to expect that carbon nanotubes and related one-dimensional carbon nanostructures may be promising candidates for high-performance thermoelectric materials.
    Keywords: ATK, Application, thermoelectric properties, molecular dynamics, graphene, nanotubes
    Area: graphene; nanotubes; thermo
    BibTeX:
    @incollection{Liu2014,
      author = {Liu, H.J.},
      title = {Thermoelectric Properties of Carbon Nanotubes and Related One-Dimensional Structures},
      booktitle = {Lecture Notes in Nanoscale Science and Technology},
      publisher = {Springer International Publishing},
      year = {2014},
      volume = {16},
      pages = {363-391},
      doi = {http://dx.doi.org/10.1007/978-3-319-02012-9_12}
    }
    
    Li Ming-Jun, Long Meng-Qiu & Xu Hui Effects of the Bridging Bond on Electronic Transport in a D-B-A Device 2013 Chinese Physics Letters
    Vol. 30(8), 087201- 
    DOI  
    Abstract: By using density functional theory combined with a nonequilibrium Green's functions approach, the electronic transport properties of different bridges connecting benzene-based heterojunction molecular devices are investigated. We focus on the effects of the bridging bond polarity and its bond length. Our results show that the polar bond plays a significant role in determining the overall conductance of the molecular devices. The effects of a current plateau and the negative differential resistance can be observed. These simulation results suggest that the proposed models may be helpful for designing practical molecular devices.
    Keywords: ATK, Application, molecular electronics
    Area: molecular electronics
    BibTeX:
    @article{Ming-Jun2013,
      author = {Ming-Jun, Li and Meng-Qiu, Long and Hui, Xu},
      title = {Effects of the Bridging Bond on Electronic Transport in a D-B-A Device},
      journal = {Chinese Physics Letters},
      year = {2013},
      volume = {30},
      number = {8},
      pages = {087201--},
      doi = {http://dx.doi.org/10.1088/0256-307X/30/8/087201}
    }
    
    R Quhe, J Ma, Z Zeng, K Tang, J Zheng, Y Wang, Z Ni, L Wang, Z Gao, J Shi & J Lu Tunable band gap in few-layer graphene by surface adsorption. 2013 Sci Rep
    Vol. 3, 1794 
    DOI  
    Abstract: There is a tunable band gap in ABC-stacked few-layer graphene (FLG) via applying a vertical electric field, but the operation of FLG-based field effect transistor (FET) requires two gates to create a band gap and tune channel's conductance individually. Using first principle calculations, we propose an alternative scheme to open a band gap in ABC-stacked FLG namely via single-side adsorption. The band gap is generally proportional to the charge transfer density. The capability to open a band gap of metal adsorption decreases in this order: K/Al > Cu/Ag/Au > Pt. Moreover, we find that even the band gap of ABA-stacked FLG can be opened if the bond symmetry is broken. Finally, a single-gated FET based on Cu-adsorbed ABC-stacked trilayer graphene is simulated. A clear transmission gap is observed, which is comparable with the band gap. This renders metal-adsorbed FLG a promising channel in a single-gated FET device.
    Keywords: ATK; Application; graphene; few-layer graphene; field-effect transistor
    Area: graphene
    BibTeX:
    @article{Quhe2013,
      author = {Quhe, R and Ma, J and Zeng, Z and Tang, K and Zheng, J and Wang, Y and Ni, Z and Wang, L and Gao, Z and Shi, J and Lu, J},
      title = {Tunable band gap in few-layer graphene by surface adsorption.},
      journal = {Sci Rep},
      year = {2013},
      volume = {3},
      pages = {1794},
      doi = {http://dx.doi.org/10.1038/srep01794}
    }
    
    Kamal K. Saha & Branislav K. Nikolic Negative differential resistance in graphene-nanoribbon-carbon-nanotube crossbars: a first-principles multiterminal quantum transport study 2013 Journal of Computational Electronics
    Vol. 12(4)Journal of Computational Electronics, 542-552 
    DOI  
    Abstract: We simulate quantum transport between a graphene nanoribbon (GNR) and a single-walled carbon nanotube (CNT) where electrons traverse vacuum gap between them. The GNR covers CNT over a nanoscale region while their relative rotation is 90 degrees, thereby forming a four-terminal crossbar where the bias voltage is applied between CNT and GNR terminals. The CNT and GNR are chosen as either semiconducting (s) or metallic (m) based on whether their two-terminal conductance exhibits a gap as a function of the Fermi energy or not, respectively. We find nonlinear current-voltage (I-V) characteristics in all three investigated devices - mGNR-sCNT, sGNR-sCNT and mGNR-mCNT crossbars - which are asymmetric with respect to changing the bias voltage from positive to negative. Furthermore, the I-V characteristics of mGNR-sCNT crossbar exhibits negative differential resistance (NDR) with low onset voltage V NDR ~0.25 V and peak-to-valley current ratio ~2.0. The overlap region of the crossbars contains only ~460 carbon and hydrogen atoms which paves the way for nanoelectronic devices ultrascaled well below the smallest horizontal length scale envisioned by the international technology roadmap for semiconductors. Our analysis is based on the nonequilibrium Green function formalism combined with density functional theory (NEGF-DFT), where we also provide an overview of recent extensions of NEGF-DFT framework (originally developed for two-terminal devices) to multiterminal devices.
    Keywords: ATK, Application, Crossed nanowires, negative differential resistance, NDR, graphene nanoribbons, carbon nanotubes, multiterminal nanostructures, first-principles quantum transport
    Area: graphene; nanotubes
    BibTeX:
    @article{Saha2013,
      author = {Saha, Kamal K. and Nikolic, Branislav K.},
      title = {Negative differential resistance in graphene-nanoribbon-carbon-nanotube crossbars: a first-principles multiterminal quantum transport study},
      booktitle = {Journal of Computational Electronics},
      journal = {Journal of Computational Electronics},
      publisher = {Springer US},
      year = {2013},
      volume = {12},
      number = {4},
      pages = {542-552},
      doi = {http://dx.doi.org/10.1007/s10825-013-0534-z}
    }
    
    Sabyasachi Sen & Swapan Chakrabarti In silico design of a tunable molecular spin filter using chromium-carbon-chromium chains 2014 Chemical Physics
    Vol. 428(0), 34-42 
    DOI  
    Abstract: We report on the potential use of Cr-C_n-Cr as a tunable molecular spin filter. Our study reveals that by suitably engineering the number of carbon atoms between the two Cr atoms, very strong spin filter efficiency could be achieved. An even-odd oscillation has been observed both in the spin polarized conductance as well as spin filter efficiency and it is reported that only with even number of carbon atoms the spin filter efficiency of the systems become 99.99%. Results obtained from the state-of-the-art nonequilibrium Green's function based calculations has been validated by analyzing the spin polarized transmission spectra, density of states, and molecular projected self consistent Hamiltonian states obtained at specific length of the carbon chain. The modification in singly occupied highest molecular orbital on going from odd to even number of carbon atoms explains the origin of the even-odd oscillation.
    Keywords: ATK, Application, transition metal-carbon cluster, tunable molecular spin filter, spin filter efficiency, even-odd oscillation
    Area: molecular electronics; spin
    BibTeX:
    @article{Sen2014,
      author = {Sen, Sabyasachi and Chakrabarti, Swapan},
      title = {In silico design of a tunable molecular spin filter using chromium-carbon-chromium chains},
      journal = {Chemical Physics},
      year = {2014},
      volume = {428},
      number = {0},
      pages = {34--42},
      doi = {http://dx.doi.org/10.1016/j.chemphys.2013.10.022}
    }
    
    Amretashis Sengupta & Santanu Mahapatra Negative differential resistance and effect of defects and deformations in MoS2 armchair nanoribbon metal-oxide-semiconductor field effect transistor 2013 Journal of Applied Physics
    Vol. 114(19), - 
    DOI  
    Abstract: In this work, we present a study on the negative differential resistance (NDR) behavior and the impact of various deformations (like ripple, twist, wrap) and defects like vacancies and edge roughness on the electronic properties of short-channel MoS2 armchair nanoribbon MOSFETs. The effect of deformation (3-7 degree twist or wrap and 0.3-0.7 Å ripple amplitude) and defects on a 10 nm MoS2 ANR FET is evaluated by the density functional tight binding theory and the non-equilibrium Green's function approach. We study the channel density of states, transmission spectra, and the ID-VD characteristics of such devices under the varying conditions, with focus on the NDR behavior. Our results show significant change in the NDR peak to valley ratio and the NDR window with such minor intrinsic deformations, especially with the ripple.
    Keywords: ATK, Application, MoS2 nanoribbon, molybdenum compounds, negative differential resistance (NDR), deformation, field-effect transistor (FET)
    Area: hexflats
    BibTeX:
    @article{Sengupta2013b,
      author = {Sengupta, Amretashis and Mahapatra, Santanu},
      title = {Negative differential resistance and effect of defects and deformations in MoS2 armchair nanoribbon metal-oxide-semiconductor field effect transistor},
      journal = {Journal of Applied Physics},
      year = {2013},
      volume = {114},
      number = {19},
      pages = {-},
      doi = {http://dx.doi.org/10.1063/1.4833554}
    }
    
    Daniel Valencia, Jun-Qiang Lu, Jian Wu, Feng Liu, Feng Zhai & Yong-Jin Jiang Electronic transmission in graphene suppressed by interlayer interference 2013 AIP Advances
    Vol. 3(10), 102125 
    DOI  
    Abstract: We investigate electronic transport property of a graphene monolayer covered by a graphene nanoribbon. We demonstrate that electronic transmission of a monolayer can be reduced when covered by a nanoribbon. The energy at which the transmission reduction occurs depends on the width of nanoribbon. We explain the transmission reduction as interference between wavefunctions in the monolayer and the nanoribbon. Furthermore, we show that the transmission reduction of a monolayer is combinable when covered by more than one nanoribbon and we propose a concept of "combination of control" for possible nano-application designs.
    Keywords: ATK, Application, wave functions, graphene nanoribbon
    Area: graphene
    BibTeX:
    @article{Valencia2013,
      author = {Valencia, Daniel and Lu, Jun-Qiang and Wu, Jian and Liu, Feng and Zhai, Feng and Jiang, Yong-Jin},
      title = {Electronic transmission in graphene suppressed by interlayer interference},
      journal = {AIP Advances},
      year = {2013},
      volume = {3},
      number = {10},
      pages = {102125},
      doi = {http://dx.doi.org/10.1063/1.4827022}
    }
    
    Le-Jia Wang, Ai Yong, Kai-Ge Zhou, Lin Tan, Jian Ye, Guo-Ping Wu, Zhu-Guo Xu & Hao-Li Zhang Conformation-Controlled Electron Transport in Single-Molecule Junctions Containing Oligo(phenylene ethynylene) Derivatives 2013 Chem. Asian J.
    Vol. 8(8), 1901-1909 
    DOI  
    Abstract: Understanding the relationships between the molecular structure and electronic transport characteristics of single-molecule junctions is of fundamental and technological importance for future molecular electronics. Herein, we report a combined experimental and theoretical study on the single-molecule conductance of a series of oligo(phenylene ethynylene) (OPE) molecular wires, which consist of two phenyl-ethynyl-phenyl pi units with different dihedral angles. The molecular conductance was studied by scanning tunneling microscopy (STM)-based break-junction techniques under different conditions, including variable temperature and bias potential, which suggested that a coherent tunneling mechanism takes place in the OPE molecular wires with a length of 2.5 nm. The conductance of OPE molecular junctions are strongly affected by the coupling strength between the two pi systems, which can be tuned by controlling their intramolecular conformation. A cos(2theta) dependence was revealed between the molecular conductance and dihedral angles between the two conjugated units. Theoretical investigations on the basis of density functional theory and nonequilibrium Green's functions (NEGF) gave consistent results with the experimental observations and provided insights into the conformation-dominated molecular conductance.
    Keywords: ATK; Application; conducting materials; conformation analysis; electron transport; molecular electronics; single-molecule studies; experimental comparison; charge-transport; quantized conductance; orbital energies; dependence; contacts; conductivity; temperature; fabrication; transition; rectifiers
    Area: molecular electronics
    BibTeX:
    @article{Wang2013c,
      author = {Wang, Le-Jia and Yong, Ai and Zhou, Kai-Ge and Tan, Lin and Ye, Jian and Wu, Guo-Ping and Xu, Zhu-Guo and Zhang, Hao-Li},
      title = {Conformation-Controlled Electron Transport in Single-Molecule Junctions Containing Oligo(phenylene ethynylene) Derivatives},
      journal = {Chem. Asian J.},
      publisher = {WILEY-VCH Verlag},
      year = {2013},
      volume = {8},
      number = {8},
      pages = {1901--1909},
      doi = {http://dx.doi.org/10.1002/asia.201300264}
    }
    
    Z. Yang, B.L. Zhang, X.G. Liu, Y.Z. Yang, X.Y. Li, S.J. Xiong & B.S. Xu Spin-valve giant magnetoresistance in scandium-benzene sandwich cluster 2013 EPL (Europhysics Letters)
    Vol. 104(5), 50006- 
    DOI  
    Abstract: Using density functional theory and non-equilibrium Green's function method, we investigate the magnetic and transport properties of organic Sc n (C 6 H 6 ) n +1 (n=1-3) sandwich clusters. The results show that the sandwiches possess high stabilities and large magnetic moments, and our prediction is in agreement with the experimental observation. With Ni as two electrodes, significant spin-valve giant magnetoresistance was found in Sc 3 (C 6 H 6 ) 4 molecular junction. Furthermore, all the sandwiches can be viewed as a new kind of spin filter. Specially, by changing the magnetization orientation of one electrode, Sc 2 (C 6 H 6 ) 3 molecular junction could effectively control the spin orientation of the electron in the system.
    Keywords: ATK, Application, sandwich cluster, spin, experimental comparison, magnetism, single-electron transistor, complexes
    Area: molecular electronics; spin
    BibTeX:
    @article{Yang2013c,
      author = {Yang, Z. and Zhang, B. L. and Liu, X. G. and Yang, Y. Z. and Li, X. Y. and Xiong, S. J. and Xu, B. S.},
      title = {Spin-valve giant magnetoresistance in scandium-benzene sandwich cluster},
      journal = {EPL (Europhysics Letters)},
      year = {2013},
      volume = {104},
      number = {5},
      pages = {50006--},
      doi = {http://dx.doi.org/10.1209/0295-5075/104/50006}
    }
    
    Wen Yang, Lu-Hao Wang, Yang Geng, Qing-Qing Sun, Peng Zhou, Shi-Jing Ding & David Wei Zhang Atomic scale investigations of the gate controlled tunneling effect in graphyne nanoribbon 2013 Journal of Applied Physics
    Vol. 114(22), 224311 
    DOI  
    Abstract: Configuration and transport properties of zigzag graphyne nanoribbon (n=2) are investigated by means of the first-principles calculations and non-equilibrium Green's function in this work. We demonstrated the controllability of the graphyne's conductivity by gate bias, and the tunneling behavior induced by gate and drain voltages was investigated systemically. The characteristics of Id-Vd, Id-Vg, as well as the evolutions of current with electron temperature elevation were explored. The device exhibits a tunneling ratio around 10^3, and the state art of tunneling operations of the tunneling field effect transistor in this split-new material was achieved.
    Keywords: ATK; Application; electrical conductivity; graphyne nanoribbon; tunneling field-effect transistor (TFET)
    Area: graphene
    BibTeX:
    @article{Yang2013d,
      author = {Yang, Wen and Wang, Lu-Hao and Geng, Yang and Sun, Qing-Qing and Zhou, Peng and Ding, Shi-Jing and Wei Zhang, David},
      title = {Atomic scale investigations of the gate controlled tunneling effect in graphyne nanoribbon},
      journal = {Journal of Applied Physics},
      year = {2013},
      volume = {114},
      number = {22},
      pages = {224311},
      doi = {http://dx.doi.org/10.1063/1.4836876}
    }
    
    Jiaxin Zheng, Yangyang Wang, Lu Wang, Ruge Quhe, Zeyuan Ni, Wai-Ning Mei, Zhengxiang Gao, Dapeng Yu, Junjie Shi & Jing Lu Interfacial Properties of Bilayer and Trilayer Graphene on Metal Substrates 2013 Sci. Rep.
    Vol. 3, 2081 
    DOI  
    Abstract: One popular approach to prepare graphene is to grow them on transition metal substrates via chemical vapor deposition. By using the density functional theory with dispersion correction, we systematically investigate for the first time the interfacial properties of bilayer (BLG) and trilayer graphene (TLG) on metal substrates. Three categories of interfacial structures are revealed. The adsorption of B(T)LG on Al, Ag, Cu, Au, and Pt substrates is a weak physisorption, but a band gap can be opened. The adsorption of B(T)LG on Ti, Ni, and Co substrates is a strong chemisorption, and a stacking-insensitive band gap is opened for the two uncontacted layers of TLG. The adsorption of B(T)LG on Pd substrate is a weaker chemisorption, with a band gap opened for the uncontacted layers. This fundamental study also helps for B(T)LG device study due to inevitable graphene/metal contact.
    Keywords: ATK; Application; graphene;
    Area: graphene
    BibTeX:
    @article{Zheng2013b,
      author = {Zheng, Jiaxin and Wang, Yangyang and Wang, Lu and Quhe, Ruge and Ni, Zeyuan and Mei, Wai-Ning and Gao, Zhengxiang and Yu, Dapeng and Shi, Junjie and Lu, Jing},
      title = {Interfacial Properties of Bilayer and Trilayer Graphene on Metal Substrates},
      journal = {Sci. Rep.},
      publisher = {Macmillan Publishers Limited. All rights reserved},
      year = {2013},
      volume = {3},
      pages = {2081},
      doi = {http://dx.doi.org/10.1038/srep02081}
    }
    
    R. Zhou, L.C. Lew Yan Voon & Y. Zhuang Properties of two-dimensional silicon grown on graphene substrate 2013 Journal of Applied Physics
    Vol. 114(9), 093711 
    DOI  
    Abstract: The structure and electrical properties of two-dimensional (2D) sheets of silicon on a graphene substrate are studied using first-principles calculations. Two forms of corrugated silicon sheets are proposed to be energetically favorable structures. A shift of the Fermi energy level is found in both corrugated structures. Calculations of electron density show a weak coupling between the silicon layer and graphene substrate in both structures. The two forms of 2D silicon sheets turn out to be metallic and exhibit anisotropic transport properties.
    Keywords: ATK; Application; silicene; graphene; electronic structure
    Area: hexflats
    BibTeX:
    @article{Zhou2013a,
      author = {Zhou, R. and Lew Yan Voon, L. C. and Zhuang, Y.},
      title = {Properties of two-dimensional silicon grown on graphene substrate},
      journal = {Journal of Applied Physics},
      year = {2013},
      volume = {114},
      number = {9},
      pages = {093711},
      doi = {http://dx.doi.org/10.1063/1.4820473}
    }
    
    Andreas Zienert, Jörg Schuster, Reinhard Streiter & Thomas Gessner Transport in carbon nanotubes: Contact models and size effects 2010 phys. stat. sol. (b)
    Vol. 247(11-12), 3002-3005 
    DOI  
    Abstract: We present electronic transport calculations for single wall carbon nanotubes (CNTs) using two highly idealized models to describe the electrodes and their contact to the CNT. In the first model we use CNT-electrodes and in the second one we apply the wide-band approximation, neglecting any atomic structure within the electrodes. The single orbital tight-binding approximation is used to describe the electronic structure of the CNTs. This enables us to apply highly efficient decimation techniques to reduce the size of the finite central Hamiltonian. Semi-infinite CNT-electrodes can be included iteratively using a similar method. Electronic transport calculations are carried out within the Landauer formalism.
    Keywords: ATK-SE, Application, carbon nanotubes, electronic transport, Greens function, Landauer formalism
    Area: nanotubes
    BibTeX:
    @article{Zienert2010,
      author = {Zienert, Andreas and Schuster, Jörg and Streiter, Reinhard and Gessner, Thomas},
      title = {Transport in carbon nanotubes: Contact models and size effects},
      journal = {phys. stat. sol. (b)},
      publisher = {WILEY-VCH Verlag},
      year = {2010},
      volume = {247},
      number = {11-12},
      pages = {3002--3005},
      doi = {http://dx.doi.org/10.1002/pssb.201000178}
    }
    
    Andreas Zienert Electronic Transport in Metallic Carbon Nanotubes with Metal Contacts 2013 School: Chemnitz University of Technology  URL 
    Abstract: The continuous migration to smaller feature sizes puts high demands on materials and technologies for future ultra-large-scale integrated circuits. Particularly, the copper-based interconnect system will reach fundamental limits soon. Their outstanding properties make metallic carbon nanotubes (CNTs) an ideal material to partially replace copper in future interconnect architectures. Here, a low contact resistance to existing metal lines is crucial. The present thesis contributes to the theory and numerical description of electronic transport in metallic CNTs with metal contacts. Different theoretical approaches are applied to various contact models and electrode materials (Al, Cu, Pd, Ag, Pt, Au) are compared. Ballistic transport calculations are based on the non-equilibrium Greens function formalism combined with tight-binding (TB), extended Hückel theory (EHT) and density functional theory (DFT). Simplified contact models allow a qualitative investigation of both the influence of geometry and CNT length, and the strength and extent of the contact on the transport properties. In addition, such simple contact models are used to compare the influence of different electronic structure methods on transport. It is found that the semiempirical TB and EHT are inadequate to quantitatively reproduce the DFT-based results. Based on this observation, an improved set of Hückel parameters is developed, which remedies this insufficiency. A systematic investigation of different contact materials is carried out using well defined atomistic metal-CNT-metal structures, optimized in a systematic way. Analytical models for the CNT-metal interaction are proposed. Based on that, electronic transport calculations are carried out, which can be extended to large systems by applying the computationally cheap improved EHT. The metal-CNT-metal systems can then be ranked by average conductance: Ag <= Au < Cu < Pt <= Pd < Al. This corresponds qualitatively with calculated contact distances, binding energies and work functions of CNTs and metals. To gain a deeper understanding of the transport properties, the electronic structure of the metal-CNT-metal systems and their respective parts is analyzed in detail. Here, the energy resolved local density of states is a valuable tool to investigate the CNT-metal interaction and its influences on the transport.
    Keywords: ATK; ATK-SE; Application; metal-nanotube contact; contact resistance; parameter fitting
    Area: nanotubes
    BibTeX:
    @phdthesis{Zienert2013a,
      author = {Andreas Zienert},
      title = {Electronic Transport in Metallic Carbon Nanotubes with Metal Contacts},
      school = {Chemnitz University of Technology},
      year = {2013},
      url = {http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-108205}
    }
    
    Andreas Zienert, Jörg Schuster & Thomas Gessner Comparison of quantum mechanical methods for the simulation of electronic transport through carbon nanotubes 2013 Microelectronic Engineering
    Vol. 106(0), 100-105 
    DOI  
    Abstract: In the present work we study the electronic transport properties of finite length single-wall carbon nanotubes (CNTs) by comparing three different theoretical frameworks. A simple model is used to describe the electrodes and the way they are attached to both ends of the CNT. Electron transport calculations are carried out on three different levels of sophistication. That are the Landauer transport formalism in combination with single-orbital tight-binding, extended Hückel theory or density functional theory. The quantum mechanical transmission which plays a central role in Landauer theory is calculated by means of equilibrium and non-equilibrium Green's function methods. Results of the three approaches are compared and discussed.
    Keywords: ATK, Application, carbon nanotube, electronic transport, Greens's function, tight-binding, extended Hückel theory, density functional theory
    Area: nanotubes
    BibTeX:
    @article{Zienert2013b,
      author = {Zienert, Andreas and Schuster, Jörg and Gessner, Thomas},
      title = {Comparison of quantum mechanical methods for the simulation of electronic transport through carbon nanotubes},
      journal = {Microelectronic Engineering},
      year = {2013},
      volume = {106},
      number = {0},
      pages = {100--105},
      doi = {http://dx.doi.org/10.1016/j.mee.2012.12.018}
    }
    
    S. Barzilai, F. Tavazza & L.E. Levine Disparate effects of an O2 internal impurity on the elongation and quantum transport of gold and silver nanowires 2013 Journal of Applied Physics
    Vol. 114(7), 074315 
    DOI  
    Abstract: In this work, we investigated the effects of an internal O2 impurity on the conductance of elongated gold and silver nanowires (NWs) using density functional theory calculations. We found that the O2 interacts with these metallic NWs very differently. In the case of gold NWs, the presence of an internal oxygen molecule locally strengthens the wire, therefore, forcing the phase transformations connected to the thinning process (3D to 2D and 2D to single atom chain) to occur far from the oxygen. As a consequence, towards the end of the elongation, the internal O2 is located far from the main conductance channel and therefore has little influence on the conductance of the NW. In contrast, in silver NWs, the presence of an internal oxygen molecule involves a larger charge transfer from the metallic atoms to the oxygen, therefore, weakening the Ag-Ag binding. During the initial stages of the elongation, several metallic bonds adjacent to the impurity break, so that in most simulations the NW thinning takes place near the O2. This thinning mechanism places the O2 near the main conductance channel, therefore, significantly reducing the conductivity of the elongated silver NWs. For both metals, our findings agree well with the published experimental results.
    Keywords: ATK-SE, ATK, Application, mechanical properties, electric admittance, nanowires, impurities, geometry optimization; conductance; molecules
    Area: nanowires
    BibTeX:
    @article{Barzilai2013d,
      author = {Barzilai, S. and Tavazza, F. and Levine, L. E.},
      title = {Disparate effects of an O2 internal impurity on the elongation and quantum transport of gold and silver nanowires},
      journal = {Journal of Applied Physics},
      year = {2013},
      volume = {114},
      number = {7},
      pages = {074315},
      doi = {http://dx.doi.org/10.1063/1.4818956}
    }
    
    S Barzilai, F Tavazza & L E Levine Structure stability and electronic transport of gold nanowires on a BeO (001) surface 2013 Modelling and Simulation in Materials Science and Engineering
    Vol. 21(7), 075003 
    DOI  
    Abstract: Gold nanowires (NWs) exhibit remarkable structural and electrical properties, making them good candidates for practical nanoelectronic devices. For such engineering applications, alpha-wurtzite BeO may be a useful platform for supporting these NWs, because gold atoms are attracted to this surface and the atom separation of the BeO (001) surface is compatible with the Au-Au atom spacing. However, the influence of this substrate on the NW conductivity and structure is not known. Here, the stability and conductance of several Au NW configurations on BeO (001) surfaces are investigated using ab initio simulations. It was found that the beryllium-terminated surface preserves the configuration for most of the NWs while the oxygen-terminated surface changes and even repels most of the NW configurations. The electronic structure and the transmission properties of the stable cases showed small changes in the electronic structure of gold NWs due to the presence of the BeO substrate. These changes do not restrict the conduction of the NWs and even enhance it by increasing the capacity of the existing transmission channels, and forming new conduction paths.
    Keywords: ATK; Application; nanowires; BeO substrate; structural stability; transmission pathways; geometry optimization; band structure; conductance; adsorption; junctions; molecules; chains
    Area: nanowires
    BibTeX:
    @article{Barzilai2013e,
      author = {Barzilai, S and Tavazza, F and Levine, L E},
      title = {Structure stability and electronic transport of gold nanowires on a BeO (001) surface},
      journal = {Modelling and Simulation in Materials Science and Engineering},
      year = {2013},
      volume = {21},
      number = {7},
      pages = {075003},
      doi = {http://dx.doi.org/10.1088/0965-0393/21/7/075003}
    }
    
    Mausumi Chattopadhyaya, Sabyasachi Sen, Md.Mehboob Alam & Swapan Chakrabarti On site Coulomb repulsion dominates over the non-local Hartree-Fock exchange in determining the band gap of polymers 2014 Journal of Physics and Chemistry of Solids
    Vol. 75(2), 212-223 
    DOI  
    Abstract: The present study deals with the relative performance of the various density functional approaches in evaluating the band gap of polymer materials. Several density functional approximations that includes pure generalized gradient approximated (GGA) functional, meta-GGA, hybrid and range separated hybrid functionals have been used to evaluate the electrical band gap or transport gap of the studied polymers and compared with that obtained using Hubbard U corrected GGA functional (GGA+U). It has been observed that the experimental band gap of the polymers studied is satisfactorily reproducible when GGA+U approach is adopted. The band gap analyses further suggest that range separated hybrid functional, CAM-B3LYP, largely overestimates the band gap of all the polymers studied while the performance of hybrid B3LYP functional and other range separated hybrid functional like HSE is moderate. Better performance of the GGA+U method clearly indicates that short range coulomb correlation plays more significant role over the non-local Hartree-Fock (HF) exchange in determining the electrical band gap of polymer materials. It is also noticeable that the Hubbard U parameter used for the various polymers under consideration is relatively large, indicating the semi-empirical nature of the GGA+U level of calculations. The present finding will help us design new low band gap polymer through estimating band gap by the GGA+U method and this could be very useful for solar cell research.
    Keywords: ATK, Application, polymers, ab initio calculations, electronic structure
    Area: dft
    BibTeX:
    @article{Chattopadhyaya2014,
      author = {Chattopadhyaya, Mausumi and Sen, Sabyasachi and Alam, Md.Mehboob and Chakrabarti, Swapan},
      title = {On site Coulomb repulsion dominates over the non-local Hartree-Fock exchange in determining the band gap of polymers},
      journal = {Journal of Physics and Chemistry of Solids},
      year = {2014},
      volume = {75},
      number = {2},
      pages = {212--223},
      doi = {http://dx.doi.org/10.1016/j.jpcs.2013.09.018}
    }
    
    Daniel DeBrincat, Oliver Keers & John E. McGrady Can heterometallic 1-dimensional chains support current rectification? 2013 Chem. Commun.
    Vol. 49(80), 9116-9118 
    DOI  
    Abstract: To what extent can a heterometallic chain of transition metal ions generate an asymmetric current-voltage response? Density functional theory suggests that the answer depends very much on the symmetry of the dominant conduction channel: pi channels are more localised and hence afford higher rectification ratios.
    Keywords: ATK, Application, molecular electronics, rectification
    Area: molecular electronics
    BibTeX:
    @article{DeBrincat2013,
      author = {DeBrincat, Daniel and Keers, Oliver and McGrady, John E.},
      title = {Can heterometallic 1-dimensional chains support current rectification?},
      journal = {Chem. Commun.},
      publisher = {The Royal Society of Chemistry},
      year = {2013},
      volume = {49},
      number = {80},
      pages = {9116--9118},
      doi = {http://dx.doi.org/10.1039/C3CC45063E}
    }
    
    X.Q. Deng, Z.H. Zhang, C.H. Yang, H.L. Zhu & B. Liang The design of spin filter junction in zigzag graphene nanoribbons with asymmetric edge hydrogenation 2013 Organic Electronics
    Vol. 14(12), 3240-3248 
    DOI  
    Abstract: Using the non-equilibrium Green's function method combined with the density functional theory, we investigate the electronic transport properties of a heterostructure based on zigzag graphene, This heterostructure consists of H2-NZGNR-H and H-NZGNR-H. Results show that a perfect dual spin filtering effect can be realized with the parallel (P) and antiparallel (AP) magnetiesm configuration, and some magnetic domain walls (DW) at the interface between two component ribbons. The magnetic moments, DOS and PDOS, the transmission pathways and LDOS demonstrate that the edge of C-H2 bonds have important effects for magnetic and spin dependent transport properties compared to the edge of C-H bonds. Our results show that the H2-ZGNR-H/H-NZGNR-H heterostructure holds promise for magneto electronics devices which can keep steady properties when change the widths of the two component ribbons.
    Keywords: ATK, Application, Spin filtering effect, Graphene nanoribbons, Heterostructure, First-principles calculation
    Area: graphene; spin
    BibTeX:
    @article{Deng2013,
      author = {Deng, X.Q. and Zhang, Z.H. and Yang, C.H. and Zhu, H.L. and Liang, B.},
      title = {The design of spin filter junction in zigzag graphene nanoribbons with asymmetric edge hydrogenation},
      journal = {Organic Electronics},
      year = {2013},
      volume = {14},
      number = {12},
      pages = {3240--3248},
      doi = {http://dx.doi.org/10.1016/j.orgel.2013.09.041}
    }
    
    X.Q. Deng, Z.H. Zhang, G.P. Tang, Z.Q. Fan & C.H. Yang Spin filter effects in zigzag-edge graphene nanoribbons with symmetric and asymmetric edge hydrogenations 2014 Carbon
    Vol. 66(0), 646-653 
    DOI  
    Abstract: Using the non-equilibrium Greenâ's function method combined with the density functional theory, we investigate the magnetism and spin-dependent transport properties of symmetric and asymmetric zigzag-edged graphene nanoribbons (ZGNRs) passivated by monohydrogenation with [1, -1] magnetism configuration. The symmetric model H-6ZGNR-H shows a dual spin filter effect, but asymmetric H-5ZGNR-H behaves as a conductor with linear current-voltage relationships. We also investigate the magnetism and spin-dependent transport properties of H2-ZGNR-H with asymmetric edge hydrogenations, the perfect dual spin filtering effect is observed in both H2-5ZGNR-H and H2-6ZGNR-H. The transmission pathways and PDOS demonstrate that the edge of C-H2 bonds have important effects on the magnetism and spin-dependent transport properties as compared with the edge of C-H bonds.
    Keywords: ATK, Application, graphene nanoribbon, spin
    Area: graphene; spin
    BibTeX:
    @article{Deng2014,
      author = {Deng, X.Q. and Zhang, Z.H. and Tang, G.P. and Fan, Z.Q. and Yang, C.H.},
      title = {Spin filter effects in zigzag-edge graphene nanoribbons with symmetric and asymmetric edge hydrogenations},
      journal = {Carbon},
      year = {2014},
      volume = {66},
      number = {0},
      pages = {646--653},
      doi = {http://dx.doi.org/10.1016/j.carbon.2013.09.061}
    }
    
    Jing Huang, Weiyi Wang, Shangfeng Yang, Qunxiang Li & Jinlong Yang Spin-polarized transport properties of Mn@Au6 cluster 2013 Chemical Physics Letters
    Vol. 590(0), 111-115 
    DOI  
    Abstract: We explore the spin-polarized electronic structures and transport properties of Mn@Au6 cluster. The ab initio modeling is performed by combining the spin-polarized density functional theory with nonequilibrium Green's function formalism. Theoretical results clearly reveal that the central Mn atom anti-ferromagnetically couples with the Au6 ring and the cluster magnetic moment is 3.0 muB. The spin-resolved transmission spectra of Mn@Au6 sandwiched between two Li (1 0 0) electrodes exhibit robust spin filtering effect. The conductance of Mn@Au6 at the small bias voltage is mainly determined by the spin-up electrons. The findings indicate that Mn@Au6 cluster holds promise in molecular spintronics applications.
    Keywords: ATK; Application; molecular electronics; spin filtering; negative differential resistance (NDR); molecular junctions; density; device; approximation; spintronics; electronics; behavior; magnets
    Area: molecular electronics; spin
    BibTeX:
    @article{Huang2013a,
      author = {Huang, Jing and Wang, Weiyi and Yang, Shangfeng and Li, Qunxiang and Yang, Jinlong},
      title = {Spin-polarized transport properties of Mn@Au6 cluster},
      journal = {Chemical Physics Letters},
      year = {2013},
      volume = {590},
      number = {0},
      pages = {111--115},
      doi = {http://dx.doi.org/10.1016/j.cplett.2013.10.049}
    }
    
    Jianming Jia, Shin-Pon Ju, Daning Shi & Kuan-Fu Lin CO adsorption on a zigzag SiC nanotube: effects of concentration density and local torsion on transport 2013 Journal of Nanoparticle Research
    Vol. 15(10)Journal of Nanoparticle Research, 1977 
    DOI  
    Abstract: The electron transport properties of CO adsorbed SiC nanotubes as a function of concentration density and structural deformation have been characterized for the single-walled (7,0) zigzag model using a combined formalism of density-functional theory and nonequilibrium Green's function. It is found that CO adsorption can significantly suppress the transmission spectrum of SiC nanotube for a wide range of energies. As the concentration increases, a density-dependent superimposed transport gap exists and widens the initial electronic band gap of SiC nanotube. Under the same applied bias voltage, the current through SiC nanotube decreases with the increasing CO concentrations. The local torsional deformation has no effect on this essential motif. However, the current in the locally twisted system is larger than that of the undeformed one. The transmission suppression and the current differences can be attributed to the response of the localized impurity state induced by CO adsorption to density and deformation. Our results show that SiC nanotube can be a promising gas sensor for CO detection.
    Keywords: ATK; Application; SiC nanotube; CO molecules; adsorption; transport property; sensor; silicon-carbide nanotubes; carbon nanotubes; ab-initio; electronic-properties; gas sensors; molecules; functionalization; monoxide
    Area: nanotubes
    BibTeX:
    @article{Jia2013,
      author = {Jia, Jianming and Ju, Shin-Pon and Shi, Daning and Lin, Kuan-Fu},
      title = {CO adsorption on a zigzag SiC nanotube: effects of concentration density and local torsion on transport},
      booktitle = {Journal of Nanoparticle Research},
      journal = {Journal of Nanoparticle Research},
      publisher = {Springer Netherlands},
      year = {2013},
      volume = {15},
      number = {10},
      pages = {1977},
      doi = {http://dx.doi.org/10.1007/s11051-013-1977-7}
    }
    
    Dibyashree Koushik, Piyush Kumar Sinha, Neha Tyagi, R.K. Dey & Anurag Srivastava Electronic Properties of Hydrogen Terminated XO (X = Mn, Zn, Ca) Nanowires: Ab-Initio Study 2014 Quantum Matter
    Vol. 3(2), 134-145 
    DOI  
    Abstract: We have performed a DFT based ab-initio study to analyze the structural stability and electronic properties of hydrogen terminated XO (X = Mn, Zn and Ca) nanowires in their linear and zigzag geometries. The total minimum energy structures have been analyzed under revised Perdew-Burke-Ernzerhof (revPBE) type parameterized GGA potential. The stability of nanowires have been analysed with one end and both end hydrogen termination and a comparative analysis of with and without hydrogen terminated geometries in terms of structural stability, electronic band structure and density of states have been made. The study confirms the effect of hydrogen passivation on the electronic band structure, as in case of both ends H-terminated ZnO and CaO linear and zigzag configurations the band gap decreases whereas in case of MnO linear and zigzag configurations the band gap increases.
    Keywords: ATK, Application, ab-initio, CaO, electronic structure, hydrogen-termination, MnO, nanowire, ZnO
    Area: nanowires
    BibTeX:
    @article{Koushik2014,
      author = {Koushik, Dibyashree and Sinha, Piyush Kumar and Tyagi, Neha and Dey, R. K. and Srivastava, Anurag},
      title = {Electronic Properties of Hydrogen Terminated XO (X = Mn, Zn, Ca) Nanowires: Ab-Initio Study},
      journal = {Quantum Matter},
      year = {2014},
      volume = {3},
      number = {2},
      pages = {134--145},
      doi = {http://dx.doi.org/10.1166/qm.2014.1105}
    }
    
    Yu-Shen Liu, Xue-Feng Wang & Feng Chi Non-magnetic doping induced a high spin-filter efficiency and large spin Seebeck effect in zigzag graphene nanoribbons 2013 J. Mater. Chem. C
    Vol. 1(48), 8046-8051 
    DOI  
    Abstract: Based on nonequilibrium Green's functions (NGF) and density-functional theory (DFT), we investigate the magnetotransport properties and magnetothermoelectric effects in zigzag graphene nanoribbons (ZGNRs) with non-magnetic doping on the double ribbon edges. One of the carbon atoms without hydrogen saturation in each ribbon edge is replaced by one boron (B) or one nitrogen (N) atom. Compared with boron-boron (BB) and nitrogen-nitrogen (NN) double-edge doping, the boron-nitrogen (BN) double-edge doping induces a perfect spin-filter effect with 100% negative spin polarization at the Fermi level. Moreover, we find that the thermoelectric effect can be enhanced by the double-edge doping. Interestingly, the spin Seebeck effect in NN- and BN-doped ZGNRs becomes comparable with the charge Seebeck effect and even larger than it. These results originate from the spin-dependent transmission node near the Fermi level induced by the non-magnetic doping. These findings strongly suggest that the double-edge-doped ZGNRs are promising materials for spintronics and thermo-spintronics.
    Keywords: ATK, Application, graphene nanoribbon, spin, magnetotransport properties, magnetothermoelectric effects, Seebeck coefficient, doping
    Area: graphene; spin; thermo
    BibTeX:
    @article{Liu2013c,
      author = {Liu, Yu-Shen and Wang, Xue-Feng and Chi, Feng},
      title = {Non-magnetic doping induced a high spin-filter efficiency and large spin Seebeck effect in zigzag graphene nanoribbons},
      journal = {J. Mater. Chem. C},
      publisher = {The Royal Society of Chemistry},
      year = {2013},
      volume = {1},
      number = {48},
      pages = {8046--8051},
      doi = {http://dx.doi.org/10.1039/C3TC31537A}
    }
    
    Jie Ma, Chuan-Lu Yang, Li-Zhi Wang, Mei-Shan Wang & Xiao-Guang Ma Controllable low-bias negative differential resistance, switching, and rectifying behaviors of dipyrimidinyl-diphenyl induced by contact mode 2014 Physica B: Condensed Matter
    Vol. 434(0), 32-37 
    DOI  
    Abstract: The negative differential resistance (NDR) and the rectifying behaviors of a molecular device induced by a saturated hydrogen atom and contact modes are investigated. Results reveal low-bias NDR behaviors of dipyrimidinyl-diphenyl (DD) molecule without saturated H atoms. NDR behavior can be eliminated depending on the contact sites. However, the rectifying behaviors of DD-molecule with saturated H atoms are apparent for all considered contact modes. In addition, the possible contact mode of the molecule in the experiment [12] was identified by examining the effect of molecular adsorption sites on gold electrodes and saturated hydrogen atom on conductance. The mechanism underlying various properties are analyzed with the highest occupied molecular orbital, lowest unoccupied molecular orbital, and transmission spectra.
    Keywords: ATK, Application, switching, rectifying, negative differential resistance, NDR, contact sites, molecular electronics
    Area: molecular electronics
    BibTeX:
    @article{Ma2014,
      author = {Ma, Jie and Yang, Chuan-Lu and Wang, Li-Zhi and Wang, Mei-Shan and Ma, Xiao-Guang},
      title = {Controllable low-bias negative differential resistance, switching, and rectifying behaviors of dipyrimidinyl-diphenyl induced by contact mode},
      journal = {Physica B: Condensed Matter},
      year = {2014},
      volume = {434},
      number = {0},
      pages = {32--37},
      doi = {http://dx.doi.org/10.1016/j.physb.2013.10.039}
    }
    
    Y. Matsuura Spin transport in bimetallocene 2013 Journal of Applied Physics
    Vol. 114(10), 103707 
    DOI  
    Abstract: I present a theoretical study on the spin-transport behavior of bimetallocenes of cobalt or nickel, wherein electronic communication between the two metal centers can be efficiently performed via a fulvalene ligand. The transmission of electrons in the bimetallocene connected to two gold electrodes was calculated using a first-principles density functional method. Spin transport was estimated from the difference between the transmissions of the spin-up and spin-down states. Results revealed that bicobaltocene has a perfect spin-filtering effect because the supply of excess electrons to the electronic state of ferrocene causes a split in the energy levels of the spin-up and spin-down states. As surmised, it was found that spin polarization was caused by strong interactions between the two metal centers via the fulvalene ligand. Furthermore, bicobaltocene exhibited a negative differential resistance at a relatively low bias voltage.
    Keywords: ATK, Application, spin polarised transport, molecular electronics
    Area: molecular electronics; spin
    BibTeX:
    @article{Matsuura2013b,
      author = {Matsuura, Y.},
      title = {Spin transport in bimetallocene},
      journal = {Journal of Applied Physics},
      year = {2013},
      volume = {114},
      number = {10},
      pages = {103707},
      doi = {http://dx.doi.org/10.1063/1.4821041}
    }
    
    Y. Min, J.H. Fang, Z.C. Dong, C.G. Zhong, C.P. Chen & K.L. Yao Disconnected zigzag carbon nanotube as spin valve and spin filter predicted by first-principles study 2013 Physica B: Condensed Matter
    Vol. 430(0), 40-44 
    DOI  
    Abstract: The first-principles study of the spin-polarized transport of a disconnected zigzag carbon nanotube is reported. We find that the tunnel magnetoresistance ratio continuously increases and has no trend of decrease. For magnetic parallel configuration, the spin-filter ratio also increases with bias and eventually reaches 99.37%. Our results indicate that the disconnected zigzag carbon nanotubes can be used as a perfect spin-filter or spin valve.
    Keywords: ATK, Application, first-principles, carbon nanotube, magnetic properties, defects, transport properties, nonequilibrium Green's-function
    Area: nanotubes; spin
    BibTeX:
    @article{Min2013,
      author = {Min, Y. and Fang, J.H. and Dong, Z.C. and Zhong, C.G. and Chen, C.P. and Yao, K.L.},
      title = {Disconnected zigzag carbon nanotube as spin valve and spin filter predicted by first-principles study},
      journal = {Physica B: Condensed Matter},
      year = {2013},
      volume = {430},
      number = {0},
      pages = {40--44},
      doi = {http://dx.doi.org/10.1016/j.physb.2013.08.027}
    }
    
    Y. Min, J.H. Fang, C.G. Zhong, Z.C. Dong, C.P. Chen & K.L. Yao Disconnect armchair carbon nanotube as rectifier predicted by first-principles study 2014 Computational Materials Science
    Vol. 81(0), 418-422 
    DOI  
    Abstract: For electronics devices based on carbon nanotube, we propose that the localization of the density of the states can enhance the rectification effect. The proposal is confirmed according to the first-principles study of the transport characteristics of several disconnected armchair nanotubes where only one side of armchair edge is hydrogenated. We find that the rectification effect increases as the diameter of armchair carbon nanotube and has no trend of decrease, which originates from the localization of the density of states of the pristine armchair edge. Our investigations indicate that the quantum size effect is helpful for molecular or nano-scale electronics devices.
    Keywords: ATK, Application, first-principles, non-equilibrium Green's-function, density-functional theory, carbon nanotube, molecular diode
    Area: nanotubes
    BibTeX:
    @article{Min2014,
      author = {Min, Y. and Fang, J.H. and Zhong, C.G. and Dong, Z.C. and Chen, C.P. and Yao, K.L.},
      title = {Disconnect armchair carbon nanotube as rectifier predicted by first-principles study},
      journal = {Computational Materials Science},
      year = {2014},
      volume = {81},
      number = {0},
      pages = {418--422},
      doi = {http://dx.doi.org/10.1016/j.commatsci.2013.08.048}
    }
    
    Fangping Ouyang, Zhixiong Yang, Shenglin Peng, Xiaojuan Zheng & Xiang Xiong Antidot-dependent bandgap and Clar sextets in graphene antidot lattices 2014 Physica E: Low-dimensional Systems and Nanostructures
    Vol. 56(0), 222-226 
    DOI  
    Abstract: By using first-principles calculations, the bandgap of two types of graphene antidot lattices (GALs) with triangular lattice, anthrancene-removed GALs and phenanthrene-removed GALs, have been studied. One third of either GALs are semiconductors as lattice parameter varies, while the lattice parameters corresponding to semiconductors are different in the two GALs, indicating the bandgap opening of GALs depends on the antidot configuration as well as lattice parameter. The bandgap opening or not is interpreted with Clar's aromatic sextet theory. A nonzero bandgap appears in phenanthrene-removed GALs, only when the number of Clar sextets exceeds one third of the total number of hexagons in the unit cell. However, due to a long zigzag edge existing in anthrancene-removed GALs, the bandgap can be open without meeting the condition. Our results suggest that the antidot configuration is a non negligible factor on the bandgap of graphene antidot lattices.
    Keywords: ATK, Application, Graphene superlattices, Antidot, Bandgap, Clar sextets, First-principles
    Area: graphene
    BibTeX:
    @article{Ouyang2014,
      author = {Ouyang, Fangping and Yang, Zhixiong and Peng, Shenglin and Zheng, Xiaojuan and Xiong, Xiang},
      title = {Antidot-dependent bandgap and Clar sextets in graphene antidot lattices},
      journal = {Physica E: Low-dimensional Systems and Nanostructures},
      year = {2014},
      volume = {56},
      number = {0},
      pages = {222--226},
      doi = {http://dx.doi.org/10.1016/j.physe.2013.09.006}
    }
    
    Feng Pan, Ruge Quhe, Qi Ge, Jiaxin Zheng, Zeyuan Ni, Yangyang Wang, Zhengxiang Gao, Lu Wang & Jing Lu Gate-induced half-metallicity in semihydrogenated silicene 2014 Physica E: Low-dimensional Systems and Nanostructures
    Vol. 56(0), 43-47 
    DOI  
    Abstract: The first-principles calculations indicate that the semihydrogenated silicene (H@Silicene) is a ferromagnetic semiconductor. By the ab initio quantum transport theory, we study for the first time the transport properties of H@Silicene with pristine silicene as electrodes. A high on/off current ratio of 106 is obtained in the single-gated H@Silicene device. More importantly, a spin-polarized current can be generated. The spin-filter efficiency increases with the gate voltage and reaches 100% at a voltage of 1.9 V. Our results suggest that a gate voltage can induce half-metallicity in H@Silicene. Therefore, a new avenue is opened for H@Silicene in application of spintronics.
    Keywords: ATK, Application, silicene, half-metallicity, quantum transport, first-principles calculation, spin-polarized transport
    Area: hexflats; spin
    BibTeX:
    @article{Pan2014,
      author = {Pan, Feng and Quhe, Ruge and Ge, Qi and Zheng, Jiaxin and Ni, Zeyuan and Wang, Yangyang and Gao, Zhengxiang and Wang, Lu and Lu, Jing},
      title = {Gate-induced half-metallicity in semihydrogenated silicene},
      journal = {Physica E: Low-dimensional Systems and Nanostructures},
      year = {2014},
      volume = {56},
      number = {0},
      pages = {43--47},
      doi = {http://dx.doi.org/10.1016/j.physe.2013.08.011}
    }
    
    Pabitra Narayan Samanta & Kalyan Kumar Das Electron transport properties of zigzag single walled tin carbide nanotubes 2014 Computational Materials Science
    Vol. 81(0), 326-331 
    DOI  
    Abstract: A combined method of density functional theory and non-equilibrium Green's function formalism has been used to study the electron transport properties of zigzag single walled SnC nanotubes (SnCNTs) of different chiralities. Band structures of zigzag SnCNTs from (4, 0) to (6, 0) are calculated using 1 x 1 x 100 k-point sampling. Transmission coefficients are computed for (n, 0) SnCNT (n = 4, 5, 6) devices at various positive and negative bias voltages within +-2.4 V. The current-voltage (I-V) curves in this bias voltage region show negative differential resistance (NDR), which is analyzed from the transmission spectra and molecular projected self-consistent Hamiltonian (MPSH) states. The rectifying performances of these devices are investigated by calculating the rectification ratio (I+/I-) with the bias voltage.
    Keywords: ATK, Application, tin-carbide nanotubes, transmission spectra, I-V curves, NDR effects, MPSH
    Area: nanotubes
    BibTeX:
    @article{Samanta2014,
      author = {Samanta, Pabitra Narayan and Das, Kalyan Kumar},
      title = {Electron transport properties of zigzag single walled tin carbide nanotubes},
      journal = {Computational Materials Science},
      year = {2014},
      volume = {81},
      number = {0},
      pages = {326--331},
      doi = {http://dx.doi.org/10.1016/j.commatsci.2013.08.035}
    }
    
    Ravinder Singh Sawhney, Harsimran Kaur & Derick Engles Effect of the Electrodes Material on Electron Transport Through Molecular Junctions 2014 Quantum Matter
    Vol. 3(2), 127-133 
    DOI  
    Abstract: In this paper, we anatomized the influence of changing the material of electrodes on the transport properties of single molecular junction comprising acetone molecule stringed to two semi-infinite electrodes using semi empirical model. The investigation of electron transport through acetone molecule was accomplished by linking it to different metallic electrodes (Pt, Pd, Au and Ag) and a non-metallic electrode (carbon) under different bias voltages within Keldysh's non-equilibrium Green Function formulism (NEGF) using Extended Hückel (EHT) semi empirical approach. The simulated results revealed that among metallic and non-metallic electrodes, the metallic electrodes showed maximum conductance of the order of 10^-6 nS, whereas non-metallic electrodes showed conductance of the order of 10^-16 nS which is in confirmation with the results proved by other authors. By comparing the I-V curves obtained using different metallic electrodes, we perceived that gold showed maximum conductance and transmission of current amidst strongest coupling and thus affirmed to be the most effective material for electrodes for nanometer scale molecular junctions, when compared with other metallic electrodes viz. platinum, palladium, and silver.
    Keywords: ATK-SE, Application, scanning tunnelling microscope (STM), mechanically controllable break junctions (MCBJ), self-assembled mono layers (SAM), extended Huckel theory (EHT), non equilibrium Green's function (NEGF), molecular electronics
    Area: molecular electronics
    BibTeX:
    @article{Sawhney2014,
      author = {Sawhney, Ravinder Singh and Kaur, Harsimran and Engles, Derick},
      title = {Effect of the Electrodes Material on Electron Transport Through Molecular Junctions},
      journal = {Quantum Matter},
      year = {2014},
      volume = {3},
      number = {2},
      pages = {127--133},
      doi = {http://dx.doi.org/10.1166/qm.2014.1104}
    }
    
    Anurag Srivastava, Srashti Jain & A.K. Nagawat Electronic Properties of Nitrogen Doped Armchair Single Wall Nanotubes: Ab-Initio Study 2013 Quantum Matter
    Vol. 2(6), 469-473 
    DOI  
    Abstract: We have analysed the effect of nitrogen doping on electronic properties of the armchair SWCNT, using density functional theory based Atomistix ToolKit (ATK) Virtual NanoLab (VNL). The total energy calculation has been performed using generalized gradient approximation (GGA) as exchange correlation functional. Findings reveal that the introduction of two and six atoms of nitrogen at the edge of armchair SWCNT changes its metallic behavior to semiconducting and unchanged for others in the nitrogen atoms range of 0<=n<=6.
    Keywords: ATK, Application, ab-initio, armchair, electronic properties, nitrogen, single-walled carbon nanotube
    Area: nanotubes
    BibTeX:
    @article{Srivastava2013e,
      author = {Srivastava, Anurag and Jain, Srashti and Nagawat, A. K.},
      title = {Electronic Properties of Nitrogen Doped Armchair Single Wall Nanotubes: Ab-Initio Study},
      journal = {Quantum Matter},
      year = {2013},
      volume = {2},
      number = {6},
      pages = {469--473},
      doi = {http://dx.doi.org/10.1166/qm.2013.1083}
    }
    
    Kurt Stokbro & Soren Smidstrup Electron transport across a metal-organic interface: Simulations using nonequilibrium Green's function and density functional theory 2013 Phys. Rev. B
    Vol. 88(7), 075317 
    DOI  
    Abstract: We simulate the electron transport across the Au(111)-pentacene interface using nonequilibrium Green's functions and density-functional theory (NEGF-DFT), and calculate the bias-dependent electron transmission. We find that the electrical contact resistance is dominated by the formation of a Schottky barrier at the interface, and show that the conventional semiconductor transport models across Schottky barriers need to be modified in order to describe the simulation data. We present an extension of the conventional Schottky barrier transport model, which can describe our simulation results and rationalize recent experimental data.
    Keywords: ATK, Application, metal-organic interface, Schottky barrier formation, experimental comparison
    Area: molecular electronics; interfaces
    BibTeX:
    @article{Stokbro2013,
      author = {Stokbro, Kurt and Smidstrup, Soren},
      title = {Electron transport across a metal-organic interface: Simulations using nonequilibrium Green's function and density functional theory},
      journal = {Phys. Rev. B},
      publisher = {American Physical Society},
      year = {2013},
      volume = {88},
      number = {7},
      pages = {075317},
      doi = {http://dx.doi.org/10.1103/PhysRevB.88.075317}
    }
    
    K Stokbro, A Blom & S Smidstrup Atomistic simulation of a III-V p-i-n junction 2013 SISPAD, 380-383   
    Abstract: We compare the results of calculations based on tight-binding and density functional theory (DFT) for the description of an ultra-narrow two-dimensional (2D) InAs system. We first investigate the electronic structure of the 2D system to understand the effect of different surface terminations and how they are modeled using tight-binding and DFT approaches. We next set up a gated 2D InAs p-i-n junction and calculate the transistor characteristics of the system using the two different approaches.
    Keywords: ATK; Application; semiconductor; InAs; doping; transistor characteristics; FinFET
    Area: semi
    BibTeX:
    @inproceedings{Stokbro2013a,
      author = {K Stokbro and A Blom and S Smidstrup},
      title = {Atomistic simulation of a III-V p-i-n junction},
      booktitle = {SISPAD},
      year = {2013},
      pages = {380-383}
    }
    
    Qing-Qing Sun, Lu-Hao Wang, Wen Yang, Peng Zhou, Peng-Fei Wang, Shi-Jin Ding & David Wei Zhang Atomic Scale Investigation of a Graphene Nano-ribbon Based High Efficiency Spin Valve 2013 Sci. Rep.
    Vol. 3, 2921 
    DOI  
    Abstract: Graphene nanoribbons based electronic devices present many interesting physical properties. We designed and investigated the spin-dependent electron transport of a device configuration, which is easy to be fabricated, with an oxygen-terminated ZGNR central scatter region between two hydrogen-terminated ZGNR electrodes. According to the analysis based on non-equilibrium Green's function and density functional theory, the proposed device could maintain its good spin-filter performance (80% to 99%) and have a stable magneto resistance value up to 105%. The spin dependent electron transmission spectrum and space-resolve density of states are employed to investigate the physical origin of the spin-polarized current and magneto resistance.
    Keywords: ATK; Application; graphene nanoribbon; spin filter; magnetoresistance; devices
    Area: graphene; spin
    BibTeX:
    @article{Sun2013a,
      author = {Sun, Qing-Qing and Wang, Lu-Hao and Yang, Wen and Zhou, Peng and Wang, Peng-Fei and Ding, Shi-Jin and Zhang, David Wei},
      title = {Atomic Scale Investigation of a Graphene Nano-ribbon Based High Efficiency Spin Valve},
      journal = {Sci. Rep.},
      publisher = {Macmillan Publishers Limited. All rights reserved},
      year = {2013},
      volume = {3},
      pages = {2921},
      doi = {http://dx.doi.org/10.1038/srep02921}
    }
    
    Q.H. Wu, P. Zhao, D.S. Liu & G. Chen Magnetoresistance, spin filtering and negative differential resistance effects in an endohedral Fe@C60 dimer 2013 Solid State Communications
    Vol. 174(0), 5-9 
    DOI  
    Abstract: Based on non-equilibrium Green's method and density functional theory, the spin-polarized transport properties of an endohedral Fe@C60 dimer-based spintronic device are investigated. The direction of the magnetic moments of the two Fe atoms can be controlled by applying a magnetic field. The interesting magnetoresistance, spin filtering and negative differential resistance effects can be observed in this device. These phenomena are explained by the evolution of spin-dependent transmission spectra and projected density of states with the increase in bias, as well as the voltage drop distributions.
    Keywords: ATK, Application, fullerene dimer, magnetoresistance effect, spin filtering effect, negative differential resistance (NDR), giant magnetoresistance; transport-properties; 1st-principles; spintronics; electronics
    Area: fullerenes; spin
    BibTeX:
    @article{Wu2013b,
      author = {Wu, Q.H. and Zhao, P. and Liu, D.S. and Chen, G.},
      title = {Magnetoresistance, spin filtering and negative differential resistance effects in an endohedral Fe@C60 dimer},
      journal = {Solid State Communications},
      year = {2013},
      volume = {174},
      number = {0},
      pages = {5--9},
      doi = {http://dx.doi.org/10.1016/j.ssc.2013.09.020}
    }
    
    Serhan Yamacli First principles study of the voltage-dependent conductance properties of n-type and p-type graphene-metal contacts 2014 Computational Materials Science
    Vol. 81(0), 607-611 
    DOI  
    Abstract: Abstract Investigation of the conductance properties of metal-graphene contacts is essential for the future nanoelectronics technology. In this study, we focus on the conductance mechanism and the voltage-dependent transport properties of both p-type and n-type graphene-metal contacts. Copper and gold are chosen as the contact metal for n-type and p-type doped graphene-metal interface, respectively. Utilizing first principles quantum mechanical calculations with density functional theory in conjunction with Green's function formalism, transmission spectra of graphene-metal contacts and the voltage-dependent variations of the current and the resistance are obtained. Finally, it is shown that obtained resistance-voltage behaviours of graphene-metal contacts are in consistent with the results reported in the literature and the voltage-dependency of the contact resistance has to be taken into consideration for the nanoscale circuit design process.
    Keywords: ATK, Application, Graphene, Metal contact, Conductance, Transmission spectrum
    Area: graphene
    BibTeX:
    @article{Yamacli2014,
      author = {Yamacli, Serhan},
      title = {First principles study of the voltage-dependent conductance properties of n-type and p-type graphene-metal contacts},
      journal = {Computational Materials Science},
      year = {2014},
      volume = {81},
      number = {0},
      pages = {607--611},
      doi = {http://dx.doi.org/10.1016/j.commatsci.2013.09.015}
    }
    
    Zhi Yang, Baolong Zhang, Xuguang Liu, Yongzhen Yang, Xiuyan Li, Shijie Xiong & Bingshe Xu The spin-filter capability and giant magnetoresistance effect in vanadium-naphthalene sandwich cluster 2013 Organic Electronics
    Vol. 14(11), 2916-2924 
    DOI  
    Abstract: Using density functional theory and non-equilibrium Green's function technique, we performed theoretical investigations on the magnetic and transport properties of V2n(C10H8)n+1 (n = 1-4) sandwich clusters. For the ground states, our results show that all the clusters are stable and possess ferromagnetic orders. The smaller clusters have higher stabilities, and our predictions are in agreement with the experimental observation. The double exchange mechanism plays an important role in determining the magnetic properties of the systems. Furthermore, with Ni as electrodes, the clusters exhibit interesting transport properties such as significant spin-filter capability, negative differential resistance feature and giant magnetoresistance effect. These findings suggest that V2n(C10H8)n+1 sandwiches are excellent candidates for application in spintronics and organic electronics.
    Keywords: ATK; Application; sandwich cluster; spin-filter capability; giant magnetoresistance; negative differential resistance (NDR); magnetic properties; ionization energies; Stern Gerlach; benzene; complexes; ferromagnetism; nanowires; transport; metals
    Area: molecular electronics; spin
    BibTeX:
    @article{Yang2013b,
      author = {Yang, Zhi and Zhang, Baolong and Liu, Xuguang and Yang, Yongzhen and Li, Xiuyan and Xiong, Shijie and Xu, Bingshe},
      title = {The spin-filter capability and giant magnetoresistance effect in vanadium-naphthalene sandwich cluster},
      journal = {Organic Electronics},
      year = {2013},
      volume = {14},
      number = {11},
      pages = {2916--2924},
      doi = {http://dx.doi.org/10.1016/j.orgel.2013.08.016}
    }
    
    Demin Yin, Weihua Liu, Xin Li, Li Geng, Xiaoli Wang & Pu Huai Mono-bi-monolayer graphene junction introduced quantum transport channels 2013 Applied Physics Letters
    Vol. 103(17), 173519 
    DOI  
    Abstract: Quantum transport properties of mono-bi-monolayer graphene junctions (MBMGJs) are investigated via first principle calculation. The simulation results show that the MBMGJs introduce more effective quantum transport channels in comparing with a full monolayer graphene nanoribbon channel and result in significantly increased on-state current. An overlapping-MBMGJ channel with one overlapping zigzag carbon chain shows a larger current even than a full bilayer graphene channel. The robustness of the effective quantum transport channel introduced by the overlapping-MBMGJ against the variation of the length of the bilayer region is also verified.
    Keywords: ATK; Application; graphene; bilayer; monolayer; MPSH
    Area: graphene
    BibTeX:
    @article{Yin2013,
      author = {Yin, Demin and Liu, Weihua and Li, Xin and Geng, Li and Wang, Xiaoli and Huai, Pu},
      title = {Mono-bi-monolayer graphene junction introduced quantum transport channels},
      journal = {Applied Physics Letters},
      year = {2013},
      volume = {103},
      number = {17},
      pages = {173519},
      doi = {http://dx.doi.org/10.1063/1.4826694}
    }
    
    J.J. Zhang, Z.H. Zhang, J. Li, D. Wang, Z. Zhu, G.P. Tang, X.Q. Deng & Z.Q. Fan Enhanced half-metallicity in carbon-chain-linked trigonal graphene 2014 Organic Electronics
    Vol. 15(1), 65-70 
    DOI  
    Abstract: The spin polarization property of a zigzag-edge trigonal graphene (ZTG) linked with different-length carbon chains Cn is investigated theoretically. It has been found that the enhancement of such a property completely depends on that the number of carbon atoms in a chain being odd or even. If it is an even number, the spin polarization is only changed slightly due to the nearly nonmagnetic property of these carbon chains. In contrast, while it is an odd number, the spin polarization is enhanced significantly to a larger energy range, i.e., showing a prominent half-metallicity and perfect spin-filter effects, owing to interactions of the ZTG and carbon chains with the strong ferromagnetism property. Deepgoing analyses show that these results are intimately related to a polyyne-like configuration for carbon chains in nanojunctions and the transition from the bipolar magnetic semiconductor to half-metallicity. Our findings suggest that this simple structure might promise importantly potential applications for developing nano-scale spintronics devices.
    Keywords: ATK, Application, trigonal graphene, carbon chain, spin polarization, half-metallicity, MPSH
    Area: graphene; spin
    BibTeX:
    @article{Zhang2014,
      author = {Zhang, J.J. and Zhang, Z.H. and Li, J. and Wang, D. and Zhu, Z. and Tang, G.P. and Deng, X.Q. and Fan, Z.Q.},
      title = {Enhanced half-metallicity in carbon-chain-linked trigonal graphene},
      journal = {Organic Electronics},
      year = {2014},
      volume = {15},
      number = {1},
      pages = {65--70},
      doi = {http://dx.doi.org/10.1016/j.orgel.2013.10.022}
    }
    
    P. Zhao, D.S. Liu & G. Chen Energy alignment induced large rectifying behavior in endoheral fullerene dimers 2013 The Journal of Chemical Physics
    Vol. 139(8), 084318 
    DOI  
    Abstract: Using the nonequilibrium Green's function formalism combined with density functional theory for quantum transport calculation, we have investigated the electronic transport properties of three endofullerenes Na@C60C60@F, Na@C60C60, and F@C60C60. The results show that the electronic transport properties of these endofullerenes are strongly dependent upon the species inside the fullerene. A large rectifying behavior is observed in Na@C60C60, while Na@C60C60@F and F@C60C60 can only present very weak rectification. It is revealed that the alignment between the molecular levels of two C60s moieties with the applied bias is the main cause of the large rectification in Na@C60C60.
    Keywords: ATK, Application, density functional theory, fullerenes, molecular electronics
    Area: fullerenes; molecular electronics
    BibTeX:
    @article{Zhao2013f,
      author = {Zhao, P. and Liu, D. S. and Chen, G.},
      title = {Energy alignment induced large rectifying behavior in endoheral fullerene dimers},
      journal = {The Journal of Chemical Physics},
      year = {2013},
      volume = {139},
      number = {8},
      pages = {084318},
      doi = {http://dx.doi.org/10.1063/1.4818746}
    }
    
    Yan-Hong Zhou, Jing Zeng, Li-Ming Tang, Ke-Qiu Chen & W.P. Hu Giant magnetoresistance effect and spin filters in phthalocyanine-based molecular devices 2013 Organic Electronics
    Vol. 14(11), 2940-2947 
    DOI  
    Abstract: The spin transport properties of molecular devices constructed by hydrogen-phthalocyanine and transition metal (TM)-phthalocyanine molecule with zigzag graphene nanoribbon electrodes are investigated by the Keldysh nonequilibrium Green's function method in combination with the density functional theory. The results show that there exists giant magnetoresistance in both the hydrogen-phthalocyanine and the TM-phthalocyanine systems. The magnetoresistance ratio is much bigger than that found by Schmaus et al. [S. Schmaus, A. Bagrets, Y. Nahas, T. K. Yamada, A. Bork, M. Bowen, E. Beaurepaire, F. Evers, W. Wulfhekel, Nature Nanotechnology 6 (2011) 185-189] in single hydrogen-phthalocyanine-Co electrodes system. Moreover, it is found that the chromium-phthalocyanine molecular device is a good spin filtering device with nearly 100% spin filtering efficiency at a wide bias voltage region. The mechanisms are proposed for these phenomena.
    Keywords: ATK; Application; giant magnetoresistance; spin filter; phthalocyanine molecule; density functional theory; spintronic devices; single molecule; rectification
    Area: graphene; spin
    BibTeX:
    @article{Zhou2013,
      author = {Zhou, Yan-Hong and Zeng, Jing and Tang, Li-Ming and Chen, Ke-Qiu and Hu, W.P.},
      title = {Giant magnetoresistance effect and spin filters in phthalocyanine-based molecular devices},
      journal = {Organic Electronics},
      year = {2013},
      volume = {14},
      number = {11},
      pages = {2940--2947},
      doi = {http://dx.doi.org/10.1016/j.orgel.2013.08.023}
    }
    
    Neeraj Jain, S. Manhas, A.K. Aggarwal & P.K. Chaudhry Effect of Metal Contact on CNT Based Sensing of NO2 Molecules 2014 Environmental Science and Engineering, 637-639-  DOI  
    Abstract: The electronic structure of Carbon Nanotubes (CNTs) is highly sensitive to the presence of foreign molecules. Also due to the large surface area of CNTs, there is a higher chance of them getting exposed to the surrounding gas molecules. This property is utilized in CNT based gas sensing applications. In this work, we have studied a zigzag CNT (Z-CNT) and simulated the transmission spectra and I-V characteristics using Density functional theory and Extended Huckel theory. Then the change in electrical properties of the Platinum (Pt) contacted Z-CNT on adsorption of NO2 molecules was simulated. Exposure of NO2 increases the conductance of the CNT by extracting electrons from the CNT making it p-type. Higher concentration of gas molecules results in larger change in the conductance due to the accumulated effects of individual gas molecules underlining its effectiveness in the formation of a gas sensor. Pt makes a schottky contact with the zigzag CNT and it was found that there is an appreciable change in the transmission spectrum as well as I-V characteristics making Platinum contacted zigzag CNT a good material for NO2 detection. This study is aimed at understanding effect of adsorption of NO2 and Pt contact on the I-V characteristics.
    Keywords: ATK; ATK-SE; Application; CNT based sensor, CNT-metal contact; Schottky barrier
    Area: nanotubes
    BibTeX:
    @incollection{Jain2014,
      author = {Jain, Neeraj and Manhas, S. and Aggarwal, A.K. and Chaudhry, P.K.},
      title = {Effect of Metal Contact on CNT Based Sensing of NO2 Molecules},
      booktitle = {Environmental Science and Engineering},
      publisher = {Springer International Publishing},
      year = {2014},
      pages = {637-639--},
      doi = {http://dx.doi.org/10.1007/978-3-319-03002-9_162}
    }
    
    Chao Jiang, Xue-Feng Wang & Ming-Xing Zhai Spin negative differential resistance in edge doped zigzag graphene nanoribbons 2014 Carbon
    Vol. 68(3), 406-412 
    DOI  
    Abstract: Abstract The nonlinear spin-dependent transport properties in zigzag graphene nanoribbons (ZGNRs) edge doped by an atom of group III and V elements are studied systematically using density functional theory combined with non-equilibrium Green's functions. The dopant type, acceptor or donor, and the geometrical symmetry, odd or even, are found critical in determining the spin polarization of the current and the current-voltage characteristics. For ZGNRs substitutionally doped on the lower-side edge, the down (up) spin current dominates in odd-(even-) width ZGNRs under a bias voltage around 1 V. Remarkably, in even-width ZGNRs, doped by group III elements (B and Al), negative differential resistance (NDR) occurs only for down spins. The bias range of the spin NDR increases with the width of ZGNRs. The clear spin NDR is not observed in any odd-width ZGNRs nor in even-width ZGNRs doped by group V elements (N and P). This peculiar spin NDR of edge doped ZGNRs suggests potential applications in spintronics.
    Keywords: ATK; Application; graphene; negative differential resistance; NDR; spin
    Area: graphene; spin
    BibTeX:
    @article{Jiang2014,
      author = {Jiang, Chao and Wang, Xue-Feng and Zhai, Ming-Xing},
      title = {Spin negative differential resistance in edge doped zigzag graphene nanoribbons},
      journal = {Carbon},
      year = {2014},
      volume = {68},
      number = {3},
      pages = {406--412},
      doi = {http://dx.doi.org/10.1016/j.carbon.2013.11.017}
    }
    
    Ivan P. Krotnev Novel metallic field-effect transistors 2013 School: University of Toronto  URL 
    Abstract: This thesis describes a novel concept for a field-effect transistor based on metallic channels. Latest research demonstrates that the bulk (3D) properties of many materials begin to change when confined to 2D sheets, or 1D nanowires. Particularly, the bandgap increases and the density of states decreases. In this work, this effect is explored further to demonstrate its application to field-effect transistors. Certain metals such as Gold and Silver in these dimensions have extremely low density of states in particular energy regions and through gate modulation can be partially depleted from electrons thus creating conditions for field-effect. A simulation study of Gold channel FET demonstrates ION=IOF F of 30 and superior current driving capability compared to the state-of-the art 22 nm SiGe ETSOI as well as 30 nm nanotube transistors.
    Keywords: ATK; Application; semi; field-effect transistor; metallic channel;
    Area: semi
    BibTeX:
    @phdthesis{Krotnev2013,
      author = {Ivan P. Krotnev},
      title = {Novel metallic field-effect transistors},
      school = {University of Toronto},
      year = {2013},
      url = {https://tspace.library.utoronto.ca/bitstream/1807/42990/3/Krotnev_Ivan_P_201311_MASc_thesis.pdf}
    }
    
    Meng-Qiu Long, Xin-Mei Li, Jun He, Bingchu Yang & Liling Cui Electronic transport properties of transition metal (Cu, Fe) phthalocyanines connecting to v-shaped zigzag graphene nanoribbons 2014 International Journal of Modern Physics B
    Vol. 28(0), 1450019 
    DOI  
    Abstract: Using nonequlilibrium Green's functions in combination with the density-functional theory, we investigate the spin transport properties of molecular junction based on metal (Cu, Fe) phthalocyanines between V-shaped zigzag-edged graphene nanorribons. The results show that the electronic transport properties mainly depend on the center transition metal. The negative differential resistance behaviors and spin splitting phenomenon can be observed.
    Keywords: ATK; Application; graphene; molecular electronics; spin-polarized transport
    Area: graphene; spin
    BibTeX:
    @article{Long2014,
      author = {Long, Meng-Qiu and Li, Xin-Mei and He, Jun and Yang, Bingchu and Cui, Liling},
      title = {Electronic transport properties of transition metal (Cu, Fe) phthalocyanines connecting to v-shaped zigzag graphene nanoribbons},
      journal = {International Journal of Modern Physics B},
      year = {2014},
      volume = {28},
      number = {0},
      pages = {1450019},
      doi = {http://dx.doi.org/10.1142/S0217979214500192}
    }
    
    Francisco J. Martin-Martinez, Stijn Fias, Balazs Hajgato, Gregory Van Lier, Frank De Proft & Paul Geerlings. Inducing Aromaticity Patterns and Tuning the Electronic Transport of Zigzag Graphene Nanoribbons via Edge Design 2013 J. Phys. Chem. C
    Vol. 117(49)The Journal of Physical Chemistry C, 26371-26384 
    DOI  
    Abstract: Despite its remarkable electronic properties, graphene is a semimetal, or zero-band-gap semiconductor, which limits its potential applications in electronics. Cutting graphene into nanoribbons is one of the most successful approaches to opening the band gap of graphene toward applications. However, whereas armchair graphene nanoribbons exhibit semiconducting behavior, zigzag-edged structures are still semimetals. In this work, we perform periodic density functional theory (DFT) calculations on the electronic structure, together with nonequilibrium Green's function (NEGF) transport-property calculations, of different tailored-edge zigzag graphene nanoribbons. More precisely, we provide a complete description of the relation between band gap, transport properties, and aromaticity distribution along these materials, based on DFT results and Clar's sextet theory. The edge design is also shown to be applicable for finite fragments of carbon nanotubes in which the electronic confinement is similar. This ansatz provides different methods for the rational edge design of zigzag graphene nanoribbons, which induces aromaticity patterns and opens the band gap toward electronic applications. The mean bond length (MBL) geometric parameter and the six-center index (SCI) aromaticity descriptor are used to analyze the aromaticity patterns.
    Keywords: ATK; Application; graphene nanoribbon; current density
    Area: graphene
    BibTeX:
    @article{Martin-Martinez2013,
      author = {Martin-Martinez, Francisco J. and Fias, Stijn and Hajgato, Balazs and Van Lier, Gregory and De Proft, Frank and Geerlings., Paul},
      title = {Inducing Aromaticity Patterns and Tuning the Electronic Transport of Zigzag Graphene Nanoribbons via Edge Design},
      booktitle = {The Journal of Physical Chemistry C},
      journal = {J. Phys. Chem. C},
      publisher = {American Chemical Society},
      year = {2013},
      volume = {117},
      number = {49},
      pages = {26371--26384},
      doi = {http://dx.doi.org/10.1021/jp410032h}
    }
    
    Wanzhi Qiu, Phuong Nguyen & Efstratios Skafidas Graphene nanopores: electronic transport properties and design methodology 2014 Phys. Chem. Chem. Phys.
    Vol. 16(4), 1451-1459 
    DOI  
    Abstract: Graphene nanopores (GNPs) hold great promise as building blocks for electronic circuitry and sensors for biological and chemical sensing applications. Methods to design graphene nanopores that achieve desirable conduction performance and sensing characteristics have not been previously described. Here we present a study of the quantum transport properties of GNPs created by drilling pores in armchair and zigzag graphene ribbons. For the first time, our study reveals that the quantum transmission spectra of GNPs are highly tunable and GNPs with specific transport properties can be produced by properly designing pore shapes. Our investigation shows that the biological sensing capabilities of GNPs are transmission spectrum dependent, can vary dramatically, and are critically dependent on pore geometry. Our study provides design guidelines for creating graphene nanopores with specific transport properties to meet the needs of diverse applications and for developing sensitive biological/chemical sensors with required performance characteristics.
    Keywords: ATK; Application; graphene nanopores; sensor; DNA;
    Area: graphene
    BibTeX:
    @article{Qiu2014,
      author = {Qiu, Wanzhi and Nguyen, Phuong and Skafidas, Efstratios},
      title = {Graphene nanopores: electronic transport properties and design methodology},
      journal = {Phys. Chem. Chem. Phys.},
      publisher = {The Royal Society of Chemistry},
      year = {2014},
      volume = {16},
      number = {4},
      pages = {1451--1459},
      doi = {http://dx.doi.org/10.1039/C3CP53777C}
    }
    
    Wen kai Zhao, Guo min Ji & De sheng Liu Contact position and width effect of graphene electrode on the electronic transport properties of dehydrobenzoannulenne molecule under bias 2014 Physics Letters A
    Vol. 378(4), 446-452 
    DOI  
    Abstract: By applying nonequilibrium Green's function formalism in combination with density functional theory, we have investigated the electronic transport properties of dehydrobenzoannulenne molecule attached to different positions of the zigzag graphene nanoribbons (ZGNRs) electrode. The different contact positions are found to drastically turn the transport properties of these systems. The negative differential resistance (NDR) effect can be found when the ZGNRs electrodes are mirror symmetry under the xz midplane, and the mechanism of NDR has been explained. Moreover, parity limitation tunneling effect can be found in a certain symmetry two-probe system and it can completely destroy electron tunneling process. The present findings might be useful for the application of ZGNRs-based molecular devices.
    Keywords: ATK, Application, electronic transport, zigzag graphene nanoribbon, dehydrobenzoannulenne, density functional theory, non-equilibrium Green's function
    Area: graphene
    BibTeX:
    @article{Zhao2014,
      author = {Zhao, Wen-kai and Ji, Guo-min and Liu, De-sheng},
      title = {Contact position and width effect of graphene electrode on the electronic transport properties of dehydrobenzoannulenne molecule under bias},
      journal = {Physics Letters A},
      year = {2014},
      volume = {378},
      number = {4},
      pages = {446--452},
      doi = {http://dx.doi.org/10.1016/j.physleta.2013.12.006}
    }
    
    Brahim Akdim, Ruth Pachter, Steve S. Kim, Rajesh R. Naik, Tiffany R. Walsh, Steven Trohalaki, Gongyi Hong, Zhifeng Kuang & Barry L. Farmer Electronic Properties of a Graphene Device with Peptide Adsorption: Insight from Simulation 2013 ACS Appl. Mater. Interfaces
    Vol. 5(15)ACS Applied Materials & Interfaces, 7470-7477 
    DOI  
    Abstract: In this work, to explain doping behavior of single-layer graphene upon HSSYWYAFNNKT (P1) and HSSAAAAFNNKT (P1-3A) adsorption in field-effect transistors (GFETs), we applied a combined computational approach, whereby peptide adsorption was modeled by molecular dynamics simulations, and the lowest energy configuration was confirmed by density functional theory calculations. On the basis of the resulting structures of the hybrid materials, electronic structure and transport calculations were investigated. We demonstrate that pi-pi stacking of the aromatic residues and proximate peptide backbone to the graphene surface in P1 have a role in the p-doping. These results are consistent with our experimental observation of the GFET's p-doping even after a 24-h annealing procedure. Upon substitution of three of the aromatic residues to Ala in (P1-3A), a considerable decrease from p-doping is observed experimentally, demonstrating n-doping as compared to the nonadsorbed device, yet not explained based on the atomistic MD simulation structures. To gain a qualitative understanding of P1-3A's adsorption over a longer simulation time, which may differ from aromatic amino acid residues' swift anchoring on the surface, we analyzed equilibrated coarse-grain simulations performed for 500 ns. Desorption of the Ala residues from the surface was shown computationally, which could in turn affect charge transfer, yet a full explanation of the mechanism of n-doping will require elucidation of differences between various aromatic residues as dependent on peptide composition, and inclusion of effects of the substrate and environment, to be considered in future work.
    Keywords: ATK-SE; Application; graphene; molecular adsorption; molecular dynamics; doping; peptides; distributed multipole analysis; molecular-dynamics; layer graphene; binding; field; transistors; parameters; scattering; proteins; accurate
    Area: graphene
    BibTeX:
    @article{Akdim2013,
      author = {Akdim, Brahim and Pachter, Ruth and Kim, Steve S. and Naik, Rajesh R. and Walsh, Tiffany R. and Trohalaki, Steven and Hong, Gongyi and Kuang, Zhifeng and Farmer, Barry L.},
      title = {Electronic Properties of a Graphene Device with Peptide Adsorption: Insight from Simulation},
      booktitle = {ACS Applied Materials & Interfaces},
      journal = {ACS Appl. Mater. Interfaces},
      publisher = {American Chemical Society},
      year = {2013},
      volume = {5},
      number = {15},
      pages = {7470--7477},
      doi = {http://dx.doi.org/10.1021/am401731c}
    }
    
    S Barzilai, F Tavazza & L E Levine Ab initio study of the mechanical and transport properties of pure and contaminated silver nanowires 2013 Journal of Physics: Condensed Matter
    Vol. 25(32), 325303 
    DOI  
    Abstract: The mechanical properties and conductance of contaminated and pure silver nanowires were studied using density functional theory (DFT) calculations. Several nanowires containing O 2 on their surfaces were elongated along two different directions. All of the NWs thinned down to single atom chains. In most simulations, the breaking force was not affected by the presence of the O 2 , and similar fracture strengths of ~1 nN were computed for the pure and impure NWs. When the O 2 became incorporated in the single atom chain, the fracture occurred at the Ag-O bond and a lower fracture strength was found. All of the simulations showed that the impurity interacted with the silver atoms to reduce the electron density in its nearby vicinity. A variety of conductance effects were observed depending on the location of the impurity. When the impurity migrated during the elongation to the thinnest part of the NW, it reduced the conductance significantly, and an ~1 G0 conductance (usually associated with a single atom chain) was calculated for three- and two-dimensional structures. When the impurity was adjacent to the single atom chain, the conductance reduced almost to zero. However, when it stayed far from the thinnest part of the NW, the impurity had only a small influence on the conductance.
    Keywords: ATK-SE; Application; nanowires; failure; mechanical properties; deformation; gold nanowires; geometry optimization; conductance; impurities; molecules
    Area: nanowires
    BibTeX:
    @article{Barzilai2013c,
      author = {Barzilai, S and Tavazza, F and Levine, L E},
      title = {Ab initio study of the mechanical and transport properties of pure and contaminated silver nanowires},
      journal = {Journal of Physics: Condensed Matter},
      year = {2013},
      volume = {25},
      number = {32},
      pages = {325303},
      doi = {http://dx.doi.org/10.1088/0953-8984/25/32/325303}
    }
    
    Yao-Jun Dong, Xue-Feng Wang, Ming-Xing Zhai, Jian-Chun Wu, Liping Zhou, Qin Han & Xue-Mei Wu Effects of Geometry and Symmetry on Electron Transport through Graphene-Carbon-Chain Junctions 2013 J. Phys. Chem. C
    Vol. 117(37)The Journal of Physical Chemistry C, 18845-18850 
    DOI  
    Abstract: The electron transport between two zigzag graphene nanoribbons (ZGNRs) connected by carbon atomic chains has been investigated by the nonequilibrium Green's function method combined with the density functional theory. The symmetry of the orbitals in the carbon chain critically selects the modes and energies of the transporting electrons. The electron transport near the Fermi energy can be well-manipulated by the position and the number of carbon chains contacting the nanoribbons. In symmetric ZGNRs connected by a central carbon chain, a square conductance step appears at the Fermi energy because the antisymmetric modes below it are not allowed to go through the chain. These modes can additionally contribute to the conductance if side carbon chains are added in the connection. By choosing a proper geometry configuration, we can realize Ohmic contact, current stabilizer, or the negative differential resistance phenomenon in the devices.
    Keywords: ATK; Application; graphene
    Area: graphene
    BibTeX:
    @article{Dong2013,
      author = {Dong, Yao-Jun and Wang, Xue-Feng and Zhai, Ming-Xing and Wu, Jian-Chun and Zhou, Liping and Han, Qin and Wu, Xue-Mei},
      title = {Effects of Geometry and Symmetry on Electron Transport through Graphene-Carbon-Chain Junctions},
      booktitle = {The Journal of Physical Chemistry C},
      journal = {J. Phys. Chem. C},
      publisher = {American Chemical Society},
      year = {2013},
      volume = {117},
      number = {37},
      pages = {18845--18850},
      doi = {http://dx.doi.org/10.1021/jp405318b}
    }
    
    Nahashon Ndegwa Gathitu, Yingfei Chang & Jingping Zhang Anchor position and donor/acceptor effects on transport properties in fused benzene-substituted oligothiophene molecular device 2013 Physica E: Low-dimensional Systems and Nanostructures
    Vol. 54(0), 247-252 
    DOI  
    Abstract: Utilizing non-equilibrium Green's functions in combination with density-functional theory, the transport properties of molecular devices based on fused benzene-substituted oligothiophenes were explored theoretically. The results show that the positions of anchor group and push-pull substituent groups can affect the conduction properties significantly, and the favorite current direction of the investigated devices can be tuned by applied bias. The first-principle calculations demonstrate that the forward current is favorable under low bias due to the asymmetric shift of transmission peaks of those that are derived from the resonant tunneling through HOMO state, while the asymmetric localization of HOMO states under high bias is beneficial to the reverse current.
    Keywords: ATK; Application; transport property; oligothiophene; molecular device; non-equilibrium Green's function; density-functional theory; negative differential resistance (NDR); ab-initio; junctions; circuits; formula; density
    Area: molecular electronics
    BibTeX:
    @article{Gathitu2013,
      author = {Gathitu, Nahashon Ndegwa and Chang, Yingfei and Zhang, Jingping},
      title = {Anchor position and donor/acceptor effects on transport properties in fused benzene-substituted oligothiophene molecular device},
      journal = {Physica E: Low-dimensional Systems and Nanostructures},
      year = {2013},
      volume = {54},
      number = {0},
      pages = {247--252},
      doi = {http://dx.doi.org/10.1016/j.physe.2013.06.032}
    }
    
    R.K. Ghosh & S. Mahapatra Proposal for Graphene-Boron Nitride Heterobilayer-Based Tunnel FET 2013 Nanotechnology, IEEE Transactions on
    Vol. 12(5)Nanotechnology, IEEE Transactions on, 665-667 
    DOI  
    Abstract: We investigate the gate-controlled direct band-to-band tunneling (BTBT) current in a graphene-boron nitride (G-BN) heterobilayer channel-based tunnel field effect transistor. We first study the imaginary band structure of hexagonal and Bernal-stacked heterobilayers by density functional theory, which is then used to evaluate the gate-controlled current under the Wentzel-Kramers-Brillouin approximation. It is shown that the direct BTBT is probable for a certain interlayer spacing of the G-BN which depends on the stacking orders.
    Keywords: ATK; Application; III-V semiconductors, band structure, boron compounds, density functional theory, field effect transistors, graphene, stacking, tunnel transistors, wide band gap semiconductors, BTBT current, Bernal-stacked heterobilayers, C-BN, Wentzel-Kramers-Brillouin approximation, density functional theory, gate-controlled direct band-to-band tunneling current, graphene-boron nitride heterobilayer-based tunnel FET, hexagonal heterobilayers, imaginary band structure, interlayer spacing, stacking orders, tunnel field effect transistor, Graphene, Logic gates, Materials, Photonic band gap, Stacking, Transistors, Tunneling, Band-to-band tunneling, complex band structure, graphene, tunnel field effect transistor (TFET)
    Area: graphene
    BibTeX:
    @article{Ghosh2013b,
      author = {Ghosh, R.K. and Mahapatra, S.},
      title = {Proposal for Graphene-Boron Nitride Heterobilayer-Based Tunnel FET},
      booktitle = {Nanotechnology, IEEE Transactions on},
      journal = {Nanotechnology, IEEE Transactions on},
      year = {2013},
      volume = {12},
      number = {5},
      pages = {665--667},
      doi = {http://dx.doi.org/10.1109/TNANO.2013.2272739}
    }
    
    Yan-Dong Guo, Xiao-Hong Yan & Yang Xiao Conformational change-induced switching behavior in pure-carbon systems 2013 RSC Advances
    Vol. 3(37), 16672-16680 
    DOI  
    Abstract: Based on first-principles calculation, the electronic transport properties of two-one-two dimensional carbon structures, graphene(benzene)-chain-graphene(benzene), are investigated. Switching behavior induced by conformational changes is observed, even for the systems with curved and quite long carbon chains. The spatial asymmetry of transmission channels between one- and two-dimensional carbon structures is found to be the physical mechanism behind this behavior, and it can be extended to metal systems. It is also found that the orientation of a transmission channel is able to be rotated by a nanotube (or curved graphene) through the non-planar pi-conjugated orbitals to modulate the switching behavior. Based on these structures, a kind of extremely-small pure-carbon logic operators and some other devices are proposed. As atomic motion could process information directly, the switching behavior and those devices would be very useful in nanomechanics.
    Keywords: ATK; Application; graphene; conformation;
    Area: graphene
    BibTeX:
    @article{Guo2013a,
      author = {Guo, Yan-Dong and Yan, Xiao-Hong and Xiao, Yang},
      title = {Conformational change-induced switching behavior in pure-carbon systems},
      journal = {RSC Advances},
      publisher = {The Royal Society of Chemistry},
      year = {2013},
      volume = {3},
      number = {37},
      pages = {16672--16680},
      doi = {http://dx.doi.org/10.1039/C3RA41401A}
    }
    
    Rupan Preet Kaur, Ravinder Singh Sawhney, Harpinder Kaur & Ramanjyot Kaur Length-Dependant Tunneling And Hopping Mechanism In Molecular Wires 2013 International Journal of Engineering Research & Technology (IJERT)
    Vol. 2(7), 394- 
    URL 
    Abstract: The temperature-dependant electron transport characteristics of three molecular wires of different molecular lengths belonging to the family of conjugated benzene molecules were studied. In this article, the conductance values for three molecular wires consisting of different number of benzene rings and amounting to different lengths at different temperature were calculated. The percentage change in conductance values were plotted with respect to temperature for each molecular wire in this research work. We concluded that the longest molecular wire of benzene having molecular length of 17.055 Å showed the most pronounced effect of temperature on conductance, even though this value was much smaller than the value exhibited by shortest molecular wire of length 5.003 Å. The results demonstrated that the shorter wires showed highly length dependence and temperature invariant conductance, whereas the longest wire exhibited weak length dependant and temperature variant behaviour. This electron transport behaviour was observed to be changing from tunnelling in shorter length wires to the hopping in longer length wires.
    Keywords: ATK; Application; Mesoscopic Systems, Resonant Tunneling, Thermionic emission, Hopping, Coulomb blockade.
    Area: molecular electronics
    BibTeX:
    @article{Kaur2013,
      author = {Rupan Preet Kaur and Ravinder Singh Sawhney and Harpinder Kaur and Ramanjyot Kaur},
      title = {Length-Dependant Tunneling And Hopping Mechanism In Molecular Wires},
      journal = {International Journal of Engineering Research & Technology (IJERT)},
      year = {2013},
      volume = {2},
      number = {7},
      pages = {394-},
      url = {http://www.ijert.org/browse/volume-2-2013/july-2013-edition?start=50}
    }
    
    Kavita Rao Khaddeo, Anurag Srivastava & Rajnish Kurchania Electronic Properties of GaN Nanotube: Ab Initio Study 2013 Journal of Computational and Theoretical Nanoscience
    Vol. 10(9), 2066-2070 
    DOI  
    Abstract: The electronic properties of single wall (graphitic) zigzag GaN nanotubes (GaNNTs) (n, 0) (n = 3-15) with tube diameter (d_t) ranging from 3.225 Å to 16.126 Å have been analyzed using ab-initio approach. The Density Functional Theory (DFT), with LDA-PZ and GGA-PBE as exchange-correlation functional, is employed to optimize the configuration and to evaluate the band structure of GaNNT with specified tube diameter (d_t) and chirality. The computation finds that at d_t = 3.23 Å, LDA and GGA shows almost same bandgap, whereas at d_t = 13.97 Å LDA shows metallic behavior and with GGA semiconducting. Noticeable, buckling has also been seen at d_t = 11.825 Å, which increases as radius of nanotube increases. In another finding, GaNNT of single atomic layer shows smaller band gap in comparison to that of multi atomic layer and this variation has been explained in terms of presence or absences of inter layer interactions. Interestingly, the GaNNT of single atomic layer does not show monotonic, semiconducting or metallic behavior within diameter ranging from 3.225 Å to 16.126 Å.
    Keywords: ATK; Application; ab-initio, band structure, buckling, electronic properties, zigzag GaN nanotube
    Area: nanotubes
    BibTeX:
    @article{Khaddeo2013,
      author = {Khaddeo, Kavita Rao and Srivastava, Anurag and Kurchania, Rajnish},
      title = {Electronic Properties of GaN Nanotube: Ab Initio Study},
      journal = {Journal of Computational and Theoretical Nanoscience},
      year = {2013},
      volume = {10},
      number = {9},
      pages = {2066--2070},
      doi = {http://dx.doi.org/10.1166/jctn.2013.3169}
    }
    
    Ahmed Mahmoud & Paolo Lugli Study on molecular devices with negative differential resistance 2013 Applied Physics Letters
    Vol. 103(3), 033506 
    DOI  
    Abstract: This paper provides a first-principles study for the transport behavior of molecular devices exhibiting wide bias range of negative differential resistance (NDR). The devices are composed of a diphenyl-dimethyl connected to carbon chains from each side, which are then linked to gold electrodes through thiol-gold bond. The devices show an odd/even oscillating behavior: the NDR appears only for "odd" numbers of carbon atoms in the chain. We look at different device parameters in order to determine the sources of the NDR behavior. We attribute this behavior to a lack of electrons within the chain in case of "odd" number of carbon atoms.
    Keywords: ATK-SE; Application; molecular electronics; negative differential resistance; NDR;
    Area: molecular electronics
    BibTeX:
    @article{Mahmoud2013,
      author = {Mahmoud, Ahmed and Lugli, Paolo},
      title = {Study on molecular devices with negative differential resistance},
      journal = {Applied Physics Letters},
      year = {2013},
      volume = {103},
      number = {3},
      pages = {033506},
      doi = {http://dx.doi.org/10.1063/1.4813844}
    }
    
    A. Mahmoud & P. Lugli First-Principles Study of a Novel Molecular Rectifier 2013 Nanotechnology, IEEE Transactions on
    Vol. 12(5)Nanotechnology, IEEE Transactions on, 719-724 
    DOI  
    Abstract: Designing molecular structures to meet certain behavior has become an important step in the field of molecular electronics. Interestingly, linker groups between molecules and electrodes show a critical role in the characteristic of the molecular devices. In this theoretical paper, a molecular rectifier that offers rectification ratio of more than three orders of magnitude, while preserving high on-current, is designed. In addition, a thorough investigation and explanation for the quantum transport through the device is provided. The characterization developed in this paper establishes a tight relation between the transmission spectra and electrostatic potential profile of the molecular device on the one hand, and the understanding/prediction of the rectification behavior on the other hand.
    Keywords: ab initio calculations, molecular configurations, molecular electronics, rectification, rectifiers, electrostatic potential, first-principles method, linker groups, molecular devices, molecular electronics, molecular rectifier, molecular structures, quantum transport, rectification ratio, transmission spectra, Molecular devices, nonequilibrium Green's function (NEGF), oligo-phenylene vinylene (OPV), rectifiers; ATK-SE; Application
    Area: molecular electronics
    BibTeX:
    @article{Mahmoud2013a,
      author = {Mahmoud, A. and Lugli, P.},
      title = {First-Principles Study of a Novel Molecular Rectifier},
      booktitle = {Nanotechnology, IEEE Transactions on},
      journal = {Nanotechnology, IEEE Transactions on},
      year = {2013},
      volume = {12},
      number = {5},
      pages = {719--724},
      doi = {http://dx.doi.org/10.1109/TNANO.2013.2271453}
    }
    
    Tao Ouyang, Huaping Xiao, Yuee Xie, Xiaolin Wei, Yuanping Chen & Jianxin Zhong Thermoelectric properties of gamma-graphyne nanoribbons and nanojunctions 2013 Journal of Applied Physics
    Vol. 114(7), 073710 
    DOI  
    Abstract: Using the Nonequilibrium Green's function approach, we investigate the thermoelectric properties of gamma-graphyne nanostructures. Compared with the graphene nanoribbons (GNRs), gamma-graphyne nanoribbons (GYNRs) are found to possess superior thermoelectric performance. Its thermoelectric figure of merit ZT is about 3-13 times larger than that in the GNRs. Meanwhile, the results show that the thermoelectric efficiency of GYNRs decreases as the ribbon width increases, while it increases monotonically with temperature. For the gamma-graphyne nanojunctions (GYNJs), the value of ZT increases dramatically as the width discrepancy between the left and right leads becomes more obvious. This improvement is mainly originated from the fact that the enhanced thermopower and degraded thermal conductance (including the electron and phonon contributions) outweigh the reduction of electronic conductance. Moreover, it is found that the thermoelectric behavior of GYNJs also depends on the geometric shape, which is explained by analyzing the unique width distribution of phonon contributed thermal conductance of GYNRs. These findings qualify gamma-graphyne as a promising candidate for thermoelectric applications and provide useful guideline for enhancing the thermoelectric performance in experiment.
    Keywords: ATK, Application, graphyne, graphene, nanoribbons, thermoelectric effects, ZT
    Area: graphene; thermo
    BibTeX:
    @article{Ouyang2013,
      author = {Ouyang, Tao and Xiao, Huaping and Xie, Yuee and Wei, Xiaolin and Chen, Yuanping and Zhong, Jianxin},
      title = {Thermoelectric properties of gamma-graphyne nanoribbons and nanojunctions},
      journal = {Journal of Applied Physics},
      year = {2013},
      volume = {114},
      number = {7},
      pages = {073710},
      doi = {http://dx.doi.org/10.1063/1.4818616}
    }
    
    Sweta Parashar, Pankaj Srivastava & Manisha Pattanaik Electrode materials for biphenyl-based rectification devices 2013 Journal of Molecular Modeling
    Vol. 19(10)Journal of Molecular Modeling, 4467-4475 
    DOI  
    Abstract: An ab initio approach was utilized to explore the electronic transport properties of 4'-thiolate-biphenyl-4-dithiocarboxylate (TBDT) sandwiched between two electrodes made of various materials X (X=Cu, Ag, and Au). Analysis of current-voltage (I-V) characteristics, rectification performance, transmission functions, and the projected density of states (PDOS) under various external voltage biases showed that the transport properties of these constructed systems are markedly impacted by the choice of electrode materials. Further, Cu electrodes yield the best rectifying behavior, followed by Ag and then Au electrodes. Interestingly, the rectification effects can be tuned by changing the torsion angle between the two phenyl rings, as well as by stretching the contact distances between the end group and the electrodes. For Cu, the maximum rectifying ratio increases by 37 % as the contact distance changes from 1.7 Å to 1.9 Å. This is due to an increase in coupling strength asymmetry between the molecule and the electrodes. Our findings are compared with the results reported for other systems. The present calculations are helpful not only for predicting the optimal electrode material for practical applications but also for achieving better control over rectifying performance in molecular devices.
    Keywords: ATK, Application, Electrode materials, Rectification effects, Torsion angles, Stretching distances, First-principles calculations, molecular electronics
    Area: molecular electronics
    BibTeX:
    @article{Parashar2013a,
      author = {Parashar, Sweta and Srivastava, Pankaj and Pattanaik, Manisha},
      title = {Electrode materials for biphenyl-based rectification devices},
      booktitle = {Journal of Molecular Modeling},
      journal = {Journal of Molecular Modeling},
      publisher = {Springer Berlin Heidelberg},
      year = {2013},
      volume = {19},
      number = {10},
      pages = {4467-4475},
      doi = {http://dx.doi.org/10.1007/s00894-013-1938-1}
    }
    
    A. Srivastava, N. Saraf & A.K. Nagawat Conductance Analysis of Zigzag Carbon Nanotubes Under Stress: Ab-Initio Study 2013 Quantum Matter
    Vol. 2(5), 401-407 
    DOI  
    Abstract: In the present paper, an ab-initio study of zigzag single walled carbon nanotubes (CNTs), has been performed to systematically analyse the stress effects on the conductivity. The calculations were made by using Atomistix Tool-Kit Virtual Nano Lab based on density functional theory (DFT) in self-consistent manner using generalized gradient approximation (GGA) under Perdew Burke Ernzerhoff (PBE) as exchange correlation functional. GGA based study confirms that on applying stress the conductivity of nanotubes dynamically changes as either semiconducting or metallic.
    Keywords: ATK; Application; nanotube; stress-strain; mechanical properties
    Area: nanotubes
    BibTeX:
    @article{Srivastava2013d,
      author = {A. Srivastava and N. Saraf and A. K. Nagawat},
      title = {Conductance Analysis of Zigzag Carbon Nanotubes Under Stress: Ab-Initio Study},
      journal = {Quantum Matter},
      year = {2013},
      volume = {2},
      number = {5},
      pages = {401-407},
      doi = {http://dx.doi.org/10.1166/qm.2013.1071}
    }
    
    W. Tian, Y.C. Zeng & Z.H. Zhang Electronic properties of graphene nanoribbons with periodically hexagonal nanoholes 2013 Journal of Applied Physics
    Vol. 114(7), 074307 
    DOI  
    Abstract: By using the first-principles method based on the density-functional theory, electronic properties of graphene nanoribbons punched with periodic nanoholes (GNRPNHs) are studied systematically. It has been shown that the zigzag-edge GNRPNH at the nonmagnetic state is always metal regardless of neck widths, but its metallic properties is obviously weakened due to nanohole effects, and at the anti-ferromagnetic states, its spin degeneracy still remains and the energy gap has only a smaller change. While for armchair-edge GNRPNHs, the situations are complicated. As compared with the perfect AGNRs, their band gaps become smaller or larger depending on the ribbon widths satisfying W=3p+1, 3p, or 3p-1. The analysis in depth shows that underlying origins are closely related to the width and edge shape (zigzag or armchair) of the neck subprime nanoribbon and edge subprime nanoribbon, which leads to the different quantum confinement effect. And also shown is the phenomenon of the odd-even oscillation for the band gap with the change of the neck width. These findings presented here provide theoretical references for experimentally punching desirable periodic nanoholes on the graphene nanoribbons to meet the special characteristics requirements of nanodevices.
    Keywords: ATK; Application; graphene nanoribbon
    Area: graphene
    BibTeX:
    @article{Tian2013,
      author = {Tian, W. and Zeng, Y. C. and Zhang, Z. H.},
      title = {Electronic properties of graphene nanoribbons with periodically hexagonal nanoholes},
      journal = {Journal of Applied Physics},
      year = {2013},
      volume = {114},
      number = {7},
      pages = {074307},
      doi = {http://dx.doi.org/10.1063/1.4818615}
    }
    
    Shyam Trivedi, Anurag Srivastava & Rajnish Kurchania Silicene and Germanene: A First Principle Study of Electronic Structure and Effect of Hydrogenation-Passivation 2014 Journal of Computational and Theoretical Nanoscience
    Vol. 11(3), 781-788 
    DOI  
    Abstract: Using first principle calculations we have explored the structural and electronic properties of silicene (silicon analogue of graphene) and germanene (germanium analogue of graphene). The structural optimization reveals that buckled silicene and germanene are more stable than their planar counter-parts by about 0.1 and 0.35 eV respectively. In comparison to planar graphene (buckling parameter Delta = 0 Å) the germanium sheet is buckled by 0.737 Å and silicene by 0.537 Å but both have similar electronic structure with zero band gap at K point as that of graphene. Further we investigated the effects of complete hydrogenation on these materials by considering different geometrical configurations (chair, boat, table and stirrup) and found that chair-like structure has the highest binding energy per atom in comparison to other structures. Hydrogenated silicene (silicane) shows an indirect band gap of 2.23 eV while hydrogenated germanene (germanane) possess a direct band gap of 1.8 eV.
    Keywords: ATK; Application; germanene; silicene; hydrogenation; first principle; electronic structure; binding energy
    Area: hexflats
    BibTeX:
    @article{Trivedi2014a,
      author = {Trivedi, Shyam and Srivastava, Anurag and Kurchania, Rajnish},
      title = {Silicene and Germanene: A First Principle Study of Electronic Structure and Effect of Hydrogenation-Passivation},
      journal = {Journal of Computational and Theoretical Nanoscience},
      year = {2014},
      volume = {11},
      number = {3},
      pages = {781--788},
      doi = {http://dx.doi.org/10.1166/jctn.2014.3428}
    }
    
    Chengyu Yang & Quanfang Chen Electric resistance of carbon nanotube with a Cu chain: A first-principle calculation 2013 Proceedings of the Institution of Mechanical Engineers, Part N: Journal of Nanoengineering and Nanosystems
    Vol. 227(3), 115-119 
    DOI  
    Abstract: The electric resistance and transport properties of a carbon nanotube (5,5) adsorbed with a copper chain connected with two copper electrodes have been calculated by employing nonequilibrium Green's functions and Density Functional Theory. The properties of the pure carbon nanotube (5,5) with the Cu junction electrodes have also been calculated as a reference. Both the equilibrium and nonequilibrium conditions have been investigated. The results show that the resistance of the metallic carbon nanotube (5,5) has been reduced by the adsorption of a Cu chain due to the interaction between the Cu and the carbon nanotube. The change of the current-voltage curve slope is also explained in terms of transmission spectrum.
    Keywords: ATK, Application, nanotube, adsorption
    Area: nanotubes
    BibTeX:
    @article{Yang2013a,
      author = {Yang, Chengyu and Chen, Quanfang},
      title = {Electric resistance of carbon nanotube with a Cu chain: A first-principle calculation},
      journal = {Proceedings of the Institution of Mechanical Engineers, Part N: Journal of Nanoengineering and Nanosystems},
      year = {2013},
      volume = {227},
      number = {3},
      pages = {115--119},
      doi = {http://dx.doi.org/10.1177/1740349913483127}
    }
    
    G.L. Zhang, L. Pei, J. Yu, Y. Shang, H. Zhang & B. Liu Transport properties of nanowires with alternating organosilanylene and oligoethenylene units 2013 Theoretical Chemistry Accounts
    Vol. 132(9)Theoretical Chemistry Accounts, 1-7 
    DOI  
    Abstract: Transport properties of a series of sigma-pi-conjugated nanowires nSix(C=C)y (x = 2-4, y = 1-4, and n = 2-4) were studied by using non-equilibrium Green's function formalism with density functional theory. It is found that the silanylene moiety length, the ethenylene moiety length, and the whole molecular length play important roles in governing the transport properties of the nanowires: (1) the conductivity tends to be decreased with increasing the silanylene moiety length x; (2) lengthening the ethenylene moiety y is not always favorable to enhancing the conductivity; (3) the zero-bias conductance is decayed exponentially with the whole molecular length n. Further analysis indicates that the conductivities correlate well with the transmission spectra and the topology of the HOMO and LUMO states.
    Keywords: ATK; Application; theoretical study; transport property; silanylene; ethenylene; molecular electronics; polymeric organosilicon systems; negative differential resistance; ring-opening polymerization; conducting properties; molecular wires; emission spectra; silicon nanowire; radical ions; copolymers; efficient
    Area: molecular electronics; nanowires
    BibTeX:
    @article{Zhang2013b,
      author = {Zhang, G.L. and Pei, L. and Yu, J. and Shang, Y. and Zhang, H. and Liu, B.},
      title = {Transport properties of nanowires with alternating organosilanylene and oligoethenylene units},
      booktitle = {Theoretical Chemistry Accounts},
      journal = {Theoretical Chemistry Accounts},
      publisher = {Springer Berlin Heidelberg},
      year = {2013},
      volume = {132},
      number = {9},
      pages = {1-7},
      doi = {http://dx.doi.org/10.1007/s00214-013-1386-0}
    }
    
    Genghong Zhang, Yue Zheng & Biao Wang Dissimilar-electrodes-induced asymmetric characteristic and diode effect of current transport in zinc oxide tunnel junctions 2013 Journal of Applied Physics
    Vol. 114(4), 044111 
    DOI  
    Abstract: Based on the first principles simulations and quantum transport calculations, effects of dissimilar electrodes and interfaces on the current transport and relevant electrical properties in ZnO tunnel junctions as well as the mechanism of current asymmetric characteristic adjustment have been investigated. Our results show that the potential energy, built-in electric field, electron transmission probability, current, etc. in ZnO tunnel junctions can be tailored by adopting asymmetric electrode combinations. By adopting dissimilar electrodes to fabricate different potential barriers, we have performed manipulations on current transport in ZnO tunnel junctions and realized the enhancement and even the reversal of the current asymmetric characteristic. We also demonstrate that it is the different potential energy levels of the dissimilar electrodes in asymmetric tunnel junctions playing an important role in the adjustment of current asymmetry, which is innovative and different from the mechanism of current asymmetry adjustment through strain-induced piezopotential reversal. This investigation exhibits a novel and significant method for controlling or modifying the performances of electronic devices by utilizing dissimilar electrodes.
    Keywords: ATK; Application; tunnel diodes; ZnO; interfaces; tunneling junctions; work function;
    Area: interfaces; semi
    BibTeX:
    @article{Zhang2013c,
      author = {Zhang, Genghong and Zheng, Yue and Wang, Biao},
      title = {Dissimilar-electrodes-induced asymmetric characteristic and diode effect of current transport in zinc oxide tunnel junctions},
      journal = {Journal of Applied Physics},
      year = {2013},
      volume = {114},
      number = {4},
      pages = {044111},
      doi = {http://dx.doi.org/10.1063/1.4816796}
    }
    
    Sicong Zhu, Huahua Fu, Guoying Gao, Shuling Wang, Yun Ni & Kailun Yao A first principles study of novel one-dimensional organic half-metal vanadium-cyclooctatetraene wire 2013 The Journal of Chemical Physics
    Vol. 139(2), 024309 
    DOI  
    Abstract: The structural, electronic, and magnetic properties of one-dimensional vanadium-cyclooctatetraene[(V-COT)]-n wire and sandwich clusters are investigated by means of density functional theory. It is found that the (V-COT)-n SMW is half-metallic. Through the spin transportation calculations, the system for V-COT clusters coupled to gold electrodes performs nearly perfect spin filters. In addition, the I-V curve shows obviously negative differential resistance effects. These results suggest the potential applications of (V-COT)-n in spintronics.
    Keywords: ATK; Application; spin polarised transport; nanowire; organometallic compounds
    Area: nanowires; spin
    BibTeX:
    @article{Zhu2013b,
      author = {Zhu, Sicong and Fu, Huahua and Gao, Guoying and Wang, Shuling and Ni, Yun and Yao, Kailun},
      title = {A first principles study of novel one-dimensional organic half-metal vanadium-cyclooctatetraene wire},
      journal = {The Journal of Chemical Physics},
      year = {2013},
      volume = {139},
      number = {2},
      pages = {024309},
      doi = {http://dx.doi.org/10.1063/1.4813406}
    }
    
    Lin Zhu, Meichun Qian & Shiv N. Khanna Unusually large spin polarization and magnetoresistance in a FeMg8-FeMg8 superatomic dimer 2013 The Journal of Chemical Physics
    Vol. 139(6), 064306 
    DOI  
    Abstract: Electronic transport across a FeMg8 magnetic superatom and its dimer has been investigated using a density functional theory combined with Keldysh nonequilibrium Green's-function formalism. For a single cluster, our studies for the cluster supported in various orientations on a Au(100) surface show that the transport is sensitive to the contact geometry. Investigations covering the cases where the axes of Mg square antiprism are 45 degrees, perpendicular, and parallel to the transport direction, show that the equilibrium conductance, transferred charge, and current polarizations can all change significantly with orientation. Our studies on the transport across a magnetic superatom dimer FeMg8-FeMg8 focus on the effect of electrode contact distance and the support. The calculated I-V curves show negative differential resistance behavior at larger electrode-cluster contact distances. Further, the equilibrium conductance in ferromagnetic state shows an unusually high spin polarization that is about 81.48% for specific contact distance, and a large magnetoresistance ratio exceeding 500% is also found. The results show that the superatom assemblies can provide unusual transport characteristics, and that the spin polarization and magnetoresistance can be controlled via the contact geometry.
    Keywords: ATK; Application; electrical contacts; dimer; spin; magnetoresistance; building-blocks; large systems; transport; clusters; states
    Area: molecular electronics; spin
    BibTeX:
    @article{Zhu2013c,
      author = {Zhu, Lin and Qian, Meichun and Khanna, Shiv N.},
      title = {Unusually large spin polarization and magnetoresistance in a FeMg8-FeMg8 superatomic dimer},
      journal = {The Journal of Chemical Physics},
      year = {2013},
      volume = {139},
      number = {6},
      pages = {064306},
      doi = {http://dx.doi.org/10.1063/1.4817335}
    }
    
    S. Barzilai, F. Tavazza & L.E. Levine Sensitivity of gold nano-conductors to common contaminations: ab initio results 2013 Journal of Materials Science
    Vol. 48(19)Journal of Materials Science, 6619-6624 
    DOI  
    Abstract: Gold nanowire chains are considered a good candidate for nanoelectronic devices because they exhibit remarkable structural and electrical properties. A previous study shows that the beryllium-terminated BeO (0001) surface may be a useful platform for supporting nano gold conductors, since it preserves the nano-wire configuration, does not restrict its conductivity, and even enhances it. However, the influence of contamination on the conductivity of such conductors is unknown. Here, ab initio simulations were performed to determine the effect of commonly adsorbed contaminants (H2O and O2) on the conductivity of gold nano-conductors. We found that the presence of adsorbed impurities does not alter the good conductive ability of the conductors under examination.
    Keywords: ATK; Application; impurities; ballistic conductance; metallic nanowire;
    Area: nanowires
    BibTeX:
    @article{Barzilai2013b,
      author = {Barzilai, S. and Tavazza, F. and Levine, L.E.},
      title = {Sensitivity of gold nano-conductors to common contaminations: ab initio results},
      booktitle = {Journal of Materials Science},
      journal = {Journal of Materials Science},
      publisher = {Springer US},
      year = {2013},
      volume = {48},
      number = {19},
      pages = {6619-6624},
      doi = {http://dx.doi.org/10.1007/s10853-013-7460-0}
    }
    
    Yan-Dong Guo, Xiao-Hong Yan & Yang Xiao Electrical control of the spin polarization of a current in "pure-carbon" systems based on partially hydrogenated graphene nanoribbon 2013 Journal of Applied Physics
    Vol. 113(24), - 
    DOI  
    Abstract: Controlling a spin current by electrical means and eliminating the use of ferromagnetic contacts becomes a focus of research in spintronics, as compared with conventional magnetic control methods, electrical one could reduce the dimensions and energy consumption of integrated devices. Inspired by recent progress of controlling the hydrogenation on graphene [Xie et al., Appl. Phys. Lett. 98, 193113 (2011)], we investigate the electronic structure and spin-current transport of partially hydrogenated zigzag graphene nanoribbon (ZGNR) with various hydrogenation geometries, through first-principles calculations. It is found that for ZGNR in ferromagnetic edge-coupling state, near-edge hydrogenation would suppress the magnetization on the edge of ZGNR, and lower down the transmission around EF to zero except two peaks, which reside discretely on both sides of EF with opposite spins. Based on this feature, we propose and demonstrate a three-terminal device, where the spin polarization of the current can be modulated by gate voltage (Vg ) to vary from (almost) 100% to -100%, which could serve as a perfect electrically-controlled "pure-carbon" dual-spin filter. Especially, the spin polarization varies gradually with Vg , so a current with any ratio of spin-up to spin-down electron numbers can be achieved. Moreover, the influences of ZGNR width and hydrogenation-region length on the system's performance are also discussed and a large range of ZGNR configurations are found to be suitable for the application of such a device.
    Keywords: ATK; Application; graphene nanoribbon; hydrogenation; spin; device; electronics
    Area: graphene; spin
    BibTeX:
    @article{Guo2013,
      author = {Guo, Yan-Dong and Yan, Xiao-Hong and Xiao, Yang},
      title = {Electrical control of the spin polarization of a current in "pure-carbon" systems based on partially hydrogenated graphene nanoribbon},
      journal = {Journal of Applied Physics},
      year = {2013},
      volume = {113},
      number = {24},
      pages = {-},
      doi = {http://dx.doi.org/10.1063/1.4811716}
    }
    
    Mudassir M. Husain Transition from Carbon Nanoballs to Nanocapsules With Reference To Structural and Molecular Electronic Properties 2013 International Journal of Research in Engineering and Science
    Vol. 1(1), 36-47 
    URL 
    Abstract: We have investigated theoretically the variation in energetics and electronic properties during the gradual transition from spherical or nearly spherical form (as in case of armchair) to capsule formation. The zigzag and armchair configurations of carbon nanostructures with different length to diameter (l/d) ratio have been studied. Zigzag C80 and (9,0) single wall nanocapsules, armchair C70 and (5,5) carbon nanocapsules (Cncs) system have been theoretically investigated. We have used semi-empirical molecular orbital method, at the level of PM3 type quantum mechanical model. The geometry of these molecular systems has been suitably optimized. The parameters studied are various molecular properties, energy values, frontier orbital (HOMO and LUMO) energies, heats of formation, interfrontier energy gap (Eg), density of states (DOS), electron difference density (EDD) and electrostatic difference potential (EDP) of the capsules. The structures studied were found to be stable with a minimum energy band gap respectively of 3.73 and 4.66 eV, in case of zigzag and armchair configuration and exhibit insulating properties.
    Keywords: ATK; Application; Carbon nanocapsule, frontier orbitals, density of states (DOS), electron difference density (EDD), electrostatic difference potential (EDP)
    Area: fullerenes
    BibTeX:
    @article{Husain2013,
      author = {Mudassir M. Husain},
      title = {Transition from Carbon Nanoballs to Nanocapsules With Reference To Structural and Molecular Electronic Properties},
      journal = {International Journal of Research in Engineering and Science},
      year = {2013},
      volume = {1},
      number = {1},
      pages = {36-47},
      url = {http://ijres.org/v1i1.html}
    }
    
    Mudassir M. Husain Carbon Dioxide Adsorption on Single Walled Bamboo-Like Carbon Nanotubes (SWBCNT): A Computational Study 2013 International Journal of Research in Engineering and Science
    Vol. 1(2), 13-26 
    URL 
    Abstract: Adsorption of CO2 on single walled (12,0) and (5,5) bamboo-like carbon nanotubes (SWBCNT) has been investigated theoretically. Adsorption of CO2 at 12 different sites is calculated on the surface of these tubes. The advantage of using BCNTs is the multiple number of potential binding sites available near the partition wall. On them, CO2 can get adsorbed and the number is greater as compared to normal SWCNTs. It has been observed in BCNTs, that the CO2 molecule gets absorbed via chemisorption at most of the sites. The mechanism is that the molecule breaks and the oxygen atom binds to the carbon atom of BCNT surface, changing sp2 to sp3 hybrization. The adsorption has been interpreted with reference to change in structural and electronic properties e.g. length, diameter, bond length, charge transfer and energy band gap of tubes. Our findings show that the molecule is adsorbed more strongly with larger adsorption energy on (12,0) surface than on the (5,5). The calculated value of adsorption energy in the present work is greater than the values reported previously on SWCNTs. For the first time the adsorption of any gas has been carried out on SWBCNTs.
    Keywords: ATK; Application; Bamboo-like carbon nanotubes, CO2 , adsorption, physisorption, chemisorption
    Area: fullerenes
    BibTeX:
    @article{Husain2013a,
      author = {Mudassir M. Husain},
      title = {Carbon Dioxide Adsorption on Single Walled Bamboo-Like Carbon Nanotubes (SWBCNT): A Computational Study},
      journal = {International Journal of Research in Engineering and Science},
      year = {2013},
      volume = {1},
      number = {2},
      pages = {13-26},
      url = {http://ijres.org/v1i2.html}
    }
    
    Neeraj K. Jaiswal & Pankaj Srivastava Tailoring the Electronic Structure of Zigzag Graphene Nanoribbons via Cu Impurities 2013 Journal of Computational and Theoretical Nanoscience
    Vol. 10(6), 1441-1445 
    DOI  
    Abstract: We employed density functional theory based spin polarised calculations to explore the structural stability and electronic properties of ZGNR using Cu as a terminating element as well as a substitutional dopant at various sites. In both the cases (termination and doping) Cu impurities affect the electronic properties of nanoribbons in a different way. The calculated formation energy indicates that all the structures are energetically feasible except the both edges Cu-doped ribbons. Binding energy analysis confirms that Cu impurities are strongly bound to ZGNR in all considered configurations. Moreover, ribbon edge is regarded as the most feasible site for substitutional Cu atoms in ZGNR. The electronic properties of ZGNR are sensitive to the position of Cu atoms and the ribbon width. It is revealed that ZGNR can be made semiconducting, semi-metallic, half metallic or purely metallic in nature merely by changing the ribbon width or the position of Cu atoms. The predicted half metallicity for one edge Cu-terminated ZGNR is robust against the choice of exchange correlation potential.
    Keywords: ATK; Application; binding energy; electronic structure; formation energy; spin polarization
    Area: graphene; spin
    BibTeX:
    @article{Jaiswal2013,
      author = {Jaiswal, Neeraj K. and Srivastava, Pankaj},
      title = {Tailoring the Electronic Structure of Zigzag Graphene Nanoribbons via Cu Impurities},
      journal = {Journal of Computational and Theoretical Nanoscience},
      year = {2013},
      volume = {10},
      number = {6},
      pages = {1441--1445},
      doi = {http://dx.doi.org/10.1166/jctn.2013.2868}
    }
    
    Neeraj K. Jaiswal & Pankaj Srivastava Enhanced metallicity and spin polarization in zigzag graphene nanoribbons with Fe impurities 2013 Physica E: Low-dimensional Systems and Nanostructures
    Vol. 54(0), 103-108 
    DOI  
    Abstract: We present the first principles calculations of zigzag graphene nanoribbons (ZGNR), passivated and substitutionally doped with Fe atoms. The structural stability, electronic structures and transport properties have been discussed within the frame work of density functional theory. Present calculations revealed that ribbons with a single Fe impurity per unit cell exhibit magnetic ground state independent of the site of impurity atom. All the structures have stable binding and one-edge Fe-passivated ZGNR is the most stable configuration in contrast to other considered structures including the pristine one. The electronic properties are found sensitive to the impurity site rather than the GNR width. Our findings include the possibility of converting pristine ZGNR into highly conducting ribbons which can also sustain the spin polarized current. A high spin polarization (up to 95%) has been achieved which pledges for its potential application in spintronic devices.
    Keywords: ATK; Application; graphene nanoribbon, electronic structure, spin polarization, transmission spectra, I-V characteristics; half-metallicity; transport-properties; edge; field
    Area: graphene; spin
    BibTeX:
    @article{Jaiswal2013a,
      author = {Jaiswal, Neeraj K. and Srivastava, Pankaj},
      title = {Enhanced metallicity and spin polarization in zigzag graphene nanoribbons with Fe impurities},
      journal = {Physica E: Low-dimensional Systems and Nanostructures},
      year = {2013},
      volume = {54},
      number = {0},
      pages = {103--108},
      doi = {http://dx.doi.org/10.1016/j.physe.2013.06.002}
    }
    
    Ravinder Kumar, Kulbir Kaur, Vijay Lamba & Derick Engles Modeling the Conductivity Enhancement in Doped Single-walled Carbon Nanotube (SWCNT) 2013 International Journal of Scientific & Engineering Research
    Vol. 4(6), 2254 
    URL 
    Abstract: In this work we have modeled and simulated the electronic charge transport properties for a Single-walled Carbon Nano-tube with different geometries using first-principle calculations and Nonequilibrium Green's function (NEGF) method. We modeled a Single-walled Carbon Nano-tube by rolling Armchair (4,4) or Zigzag (4,0) Graphene Nanoribbon strips with the different doping atoms (S,N,P) using semi-empirical Extended Huckle Theory (EHT) within the framework of non-equilibrium green function (NEGF). The simulations were carried in Device mode using Atomistic Tool Kit (ATK-12.8.2) and its graphical interface (custom analyzer) Virtual Nano Lab till the self-consistent results was reached. The effect of the change in conductance and I-V characteristics of the junction was visualized for various transport parameters. The distinct changes in conductance reported as the positions , concentration and type of dopants was varied in central region of the CNT between two electrodes at different bias voltages from -2V to 2 V with steps of .50 V. This suggested conductance enhancement mechanism for the charge transport in the doped Single-walled Carbon Nano-tube at different positions is important for the design of CNT based nano electronic devices.
    Keywords: ATK-SE; Application; electronic charge transport; extended Huckel theory (EHT); NEGF; SWCNT; Dopants; GNRs
    Area: nanotubes
    BibTeX:
    @article{Kumar2013,
      author = {Ravinder Kumar and Kulbir Kaur and Vijay Lamba and Derick Engles},
      title = {Modeling the Conductivity Enhancement in Doped Single-walled Carbon Nanotube (SWCNT)},
      journal = {International Journal of Scientific & Engineering Research},
      year = {2013},
      volume = {4},
      number = {6},
      pages = {2254},
      url = {http://www.ijser.org/researchpaper/Modeling-the-Conductivity-Enhancement-in-Doped-Single--walled-Carbon-Nanotube-SWCNT.pdf}
    }
    
    Jian-Chang Li & Xing Gong Diode rectification and negative differential resistance of dipyrimidinyl-diphenyl molecular junctions 2013 Organic Electronics
    Vol. 14(10), 2451-2458 
    DOI  
    Abstract: Addressable Au/dipyrimidinyl-diphenyl/Au molecular junctions are fabricated using elastic polymer stamp-printing method. To study the charge transport, current-voltage measurements are carried out from 95 up to 295 K in vacuum under both dark and light conditions. Reversible diode rectification and negative differential resistance phenomena are observed. The rectification efficiency dramatically decreases upon temperature increase or light illumination. Theoretical calculations based on the non-equilibrium Greenäs function method combined with the density functional theory is performed to elucidate the negative differential resistance behaviors. We show that the different rectification efficiency is caused by the interfacial asymmetry and the dipole effects. The negative differential resistance may be attributed to the variation of the coupling degree between the incident states of the Au electrodes and the molecular orbitals, which depends largely on the S-Au contact geometry. The direct tunneling and Fowler-Nordheim tunneling act as the main transport mechanisms for low and high bias regions, respectively. The barrier height depends largely on the light illumination, substrate temperature, and bias polarity. The distinctly different adsorbing nature of the Au/molecule interface may account for the performances.
    Keywords: ATK; Application; metal/molecule/metal junction; diode rectification; optoelectronic switching; negative differential resistance; charge transport
    Area: molecular electronics
    BibTeX:
    @article{Li2013d,
      author = {Li, Jian-Chang and Gong, Xing},
      title = {Diode rectification and negative differential resistance of dipyrimidinyl-diphenyl molecular junctions},
      journal = {Organic Electronics},
      year = {2013},
      volume = {14},
      number = {10},
      pages = {2451--2458},
      doi = {http://dx.doi.org/10.1016/j.orgel.2013.06.014}
    }
    
    Sweta Parashar, Pankaj Srivastava & Manisha Pattanaik Modeling of Cu-linked rectification devices by varying torsion angles 2013 Journal of Computational Electronics
    Vol. 12(4)Journal of Computational Electronics, 775-781 
    DOI  
    Abstract: Using the nonequilibrium Green's function (NEGF) method in combination with the density functional theory (DFT), we have analyzed the rectifying performance in Cu-linked molecular devices by varying torsion angles (0-90 degrees). The linking effect of Cu atom has been investigated by calculating current-voltage (I-V) characteristics, rectification performance, transmission functions, projected density of states (PDOS), and molecular projected self-consistent Hamiltonian (MPSH). Present calculations revealed that linking of Cu in combination with conjugated dithiocarboxylate (-CS2) and standard thiol linkers significantly affects the metal-molecule coupling asymmetry, and thus the rectifying behavior in molecular devices. Further, the subsequent studies show that the left-right combination of -CS2 linker and Cu atom displays higher rectification ratio at various torsion angles in gold-biphenyl-gold junctions than thiol and Cu linkers. The calculated results are helpful not only in predicting an optimal combination of linking groups for realistic applications but also provide the way for better control of rectification effects in molecular devices.
    Keywords: ATK; Application; linking group effects; torsion angles; rectifying performance; first-principles; molecular electronics
    Area: molecular electronics
    BibTeX:
    @article{Parashar2013,
      author = {Parashar, Sweta and Srivastava, Pankaj and Pattanaik, Manisha},
      title = {Modeling of Cu-linked rectification devices by varying torsion angles},
      booktitle = {Journal of Computational Electronics},
      journal = {Journal of Computational Electronics},
      publisher = {Springer US},
      year = {2013},
      volume = {12},
      number = {4},
      pages = {775-781},
      doi = {http://dx.doi.org/10.1007/s10825-013-0482-7}
    }
    
    You Lin Peng, Yan Hong Zhou, Xiao Hui Qiu & Li Li Zhou The Role of the Electrode Size of to the Elecronic Transport Properties 2013 Applied Mechanics and Materials
    Vol. 320(5), 88-91 
    DOI  
    Abstract: We study the size effects of the electrode to the elecronic transport properties via a molecule of benzene sandwiched between two graphene electrodes using an ab initio nonequilibrium Green's function method and density function theory. More specially, two types of electrodes are selected: one ring wide electrodes and two rings wide electrodes. We find that the current cross the system that is with two rings wide electrodes is bigger than the current that is with one ring wide electrodes. Detailed analyses of the projected density of states and the transmission spectra of the system reveals the mechanism: with wider electrodes, transmission coeffients walk nearer to the fermi energy and may make contribution to the current at applied bias voltages.
    Keywords: ATK; Application; density functional theory; projected density of states; molecular electronics
    Area: molecular electronics
    BibTeX:
    @article{Peng2013,
      author = {You Lin Peng and Yan Hong Zhou and Xiao Hui Qiu and Li Li Zhou},
      title = {The Role of the Electrode Size of to the Elecronic Transport Properties},
      journal = {Applied Mechanics and Materials},
      year = {2013},
      volume = {320},
      number = {5},
      pages = {88-91},
      doi = {http://dx.doi.org/10.4028/www.scientific.net/AMM.320.88}
    }
    
    C.Q. Qu, C.Y. Wang, L. Qiao, S.S. Yu & H.B. Li Transport properties of chemically functionalized graphene nanoribbon 2013 Chemical Physics Letters
    Vol. 578(0), 97-101 
    DOI  
    Abstract: We perform a theoretical calculation in chemically functionalized zigzag graphene nanoribbons, which are terminated with different single atoms or groups, using density functional theory and nonequilibrium Green's function techniques. The calculation results reveal that these different species of atoms and groups have a significant impact on the edge states near Fermi level as well as the spin-dependent electronic transport properties. The calculated I-V curves exhibit negative differential resistance, which can be used for application in molecular spin electronic device.
    Keywords: ATK; Application; graphene nanoribbon; chemical functionalization; spin-polarized transport; negative differential resistance (NDR); room-temperature; molecular junctions; conductance device
    Area: graphene; spin
    BibTeX:
    @article{Qu2013,
      author = {Qu, C.Q. and Wang, C.Y. and Qiao, L. and Yu, S.S. and Li, H.B.},
      title = {Transport properties of chemically functionalized graphene nanoribbon},
      journal = {Chemical Physics Letters},
      year = {2013},
      volume = {578},
      number = {0},
      pages = {97--101},
      doi = {http://dx.doi.org/10.1016/j.cplett.2013.05.071}
    }
    
    S. Sivasathya & D. John Thiruvadigal The effects of defects on electron transport in metallic single wall carbon nanotubes 2013 Nanosystems: Physics, Chemistry, Mathematics
    Vol. 4(3), 405-408 
    URL 
    Abstract: We report the transport behavior of an openend metallic single wall carbon nanotube (SWCNT) with and without local structural defects using the nonequilibrium Green's functions approach together with the density functional theory (DFT). The transmission spectra and the projected density of states for the devices such as SWCNT (3, 3), (4, 4), (5, 5) and (6, 6) with and without defects were compared. In all cases, we found that the Stone-Wales defect had an almost negligible impact on the electrical performance compared to the monovacancy defect of the single wall carbon nanotubes at the Fermi level. The current-voltage (IV) characteristics of the devices were studied using the generalized Landauer-Buttiker formalism under low bias conditions. From our results, we concluded that our systems were suitable for use in various CNT based nanoelectronic devices.
    Keywords: ATK; Application; Stone-Wales defect; density functional theory; single wall carbon nanotubes; transport properties; I-V characteristics
    Area: nanotubes
    BibTeX:
    @article{Sivasathya2013,
      author = {S. Sivasathya and D. John Thiruvadigal},
      title = {The effects of defects on electron transport in metallic single wall carbon nanotubes},
      journal = {Nanosystems: Physics, Chemistry, Mathematics},
      year = {2013},
      volume = {4},
      number = {3},
      pages = {405-408},
      url = {http://nanojournal.ifmo.ru/en/articles-2/volume4/4-3/mam-12/paper15/}
    }
    
    Anurag Srivastava & Neha Tyagi Structural and Electronic Properties of AlAs Nanocrystal: Ab-Initio Study 2013 Journal of Computational and Theoretical Nanoscience
    Vol. 10(5), 1222-1230 
    DOI  
    Abstract: Structural stability and electronic properties of AlAs nanocrystal of different sizes ranging from 0.5 to 1.4 nm have been analyzed in its zincblende (B3), wurtzite (B4), NiAs (B8), rocksalt (B1) and CsCl (B2) type phases. The electronic structure of nanocrystal is modeled within the framework of density functional theory with Perdew-Zunger (PZ) parameterized local density approximation (LDA) and Perdew, Burke and Ernzerhof parameterized generalized gradient approximation (GGA). The lattice parameters, bulk modulus and pressure derivatives of nanocrystals at different sizes have been calculated for each stable phase. The computation shows that within the size range taken into consideration the B2 type phase at 0.72 nm possess the highest bulk modulus and can be considered as mechanically much stronger amongst all other nanocrystals. The study observes that the band gap of nanocrystal in its original B3 type phase increases as the size of the nanocrystal decreases from 1.4 nm to 0.74 nm whereas the same phase is metallic within the size range of 0.5 nm to 0.6 nm.
    Keywords: ATK; Application; ab initio; bulk modulus; electronic structure; nanocrystal; semiconductors
    Area: semi
    BibTeX:
    @article{Srivastava2013b,
      author = {Srivastava, Anurag and Tyagi, Neha},
      title = {Structural and Electronic Properties of AlAs Nanocrystal: Ab-Initio Study},
      journal = {Journal of Computational and Theoretical Nanoscience},
      year = {2013},
      volume = {10},
      number = {5},
      pages = {1222--1230},
      doi = {http://dx.doi.org/10.1166/jctn.2013.2832}
    }
    
    Anurag Srivastava, Neha Tyagi & Rajeev Ahuja First-principles study of structural and electronic properties of gallium based nanowires 2013 Solid State Sciences
    Vol. 23(0), 35-41 
    DOI  
    Abstract: Abstract Structural stability and electronic properties of GaX (X = N, P, As and Sb) nanowires have been investigated using first-principles based density function theory approach. Out of linear, zigzag, square and hexagon shaped configuration, the square shaped geometry is energetically most stable. The computation of lattice parameters, bulk modulus and pressure derivatives for these Ga based nanowires observes the highest bulk modulus for hexagonal shaped GaN nanowire amongst all, suggest the mechanical strength of this geometry. Electronic band structures analysis shows the semiconducting as well as metallic behavior of these nanowires.
    Keywords: ATK, Application, semiconductors, nanowires, electronic structure, first-principles calculation, bulk modulus, semiconductors; nanowires; electronic structure; first-principles calculation; bulk modulus
    Area: nanowires; semi
    BibTeX:
    @article{Srivastava2013c,
      author = {Srivastava, Anurag and Tyagi, Neha and Ahuja, Rajeev},
      title = {First-principles study of structural and electronic properties of gallium based nanowires},
      journal = {Solid State Sciences},
      year = {2013},
      volume = {23},
      number = {0},
      pages = {35--41},
      doi = {http://dx.doi.org/10.1016/j.solidstatesciences.2013.05.014}
    }
    
    Shyam Trivedi, Anurag Srivastava & Rajnish Kurchania Electronic and Transport Properties of Silicene Nanoribbons 2014 Journal of Computational and Theoretical Nanoscience
    Vol. 11(3), 789-794 
    DOI  
    Abstract: Using Density Functional Theory (DFT) and Local Density Approximation (LDA) functional we have explored the width dependent bandgap variation and transport properties of silicene nanoribbons (SNRs). Both the armchair and zigzag SNRs are cut from the semi-metallic buckled silicon sheet. Armchair SNRs are nonmagnetic and exhibit a three family bandgap decay profile with increasing width similar to Graphene nanoribbons (GNRs). In comparison to armchair SNRs, the influence of edge spin polarization is much greater on the zigzag SNRs. The anti-ferromagnetic state is the most stable ground state for zigzag ribbons showing monotonous decrease in band gap with increasing width. Quantum transport properties have been analysed by calculating the transmission spectra of different groups of armchair and zigzag SNRs. Our result shows that wider ribbons have large transmission values.
    Keywords: ATK; Application; silicene nanoribbon;
    Area: hexflats
    BibTeX:
    @article{Trivedi2014,
      author = {Trivedi, Shyam and Srivastava, Anurag and Kurchania, Rajnish},
      title = {Electronic and Transport Properties of Silicene Nanoribbons},
      journal = {Journal of Computational and Theoretical Nanoscience},
      year = {2014},
      volume = {11},
      number = {3},
      pages = {789--794},
      doi = {http://dx.doi.org/10.1166/jctn.2014.3429}
    }
    
    Yuta Tsuji, Takayuki Semoto & Kazunari Yoshizawa A Bipodal Dicyano Anchor Unit for Single-Molecule Spintronic Devices 2013 ChemPhysChem
    Vol. 14(11), 2470-2475 
    DOI  
    Abstract: The conductance through single 7,7,8,8-tetracyanoquinodimethane (TCNQ) connected to gold electrodes is studied with the nonequilibrium Green's function method combined with density functional theory. The aim of the study is to derive the effect of a dicyano anchor group, =C(CN)2, on energy level alignment between the electrode Fermi level and a molecular energy level. The strong electron-withdrawing nature of the dicyano anchor group lowers the LUMO level of TCNQ, resulting in an extremely small energy barrier for electron injection. At zero bias, electron transfer from electrodes easily occurs and, as a consequence, the anion radical state of TCNQ with a magnetic moment is formed. The unpaired electron in the TCNQ anion radical causes an exchange splitting between the spin-alpha and spin-beta transmission spectra, allowing the single TCNQ junction to act as a spin-filtering device.
    Keywords: atk; application; adsorption; cyanides; density functional calculations; electron transport; molecular devices; molecular electronics; spintronics; negative differential resistance (NDR); electron-transport; charge transport; metal junctions; conductance; chemistry; radicals; sulfides; surfaces
    Area: molecular electronics; spin
    BibTeX:
    @article{Tsuji2013,
      author = {Tsuji, Yuta and Semoto, Takayuki and Yoshizawa, Kazunari},
      title = {A Bipodal Dicyano Anchor Unit for Single-Molecule Spintronic Devices},
      journal = {ChemPhysChem},
      publisher = {WILEY-VCH Verlag},
      year = {2013},
      volume = {14},
      number = {11},
      pages = {2470--2475},
      doi = {http://dx.doi.org/10.1002/cphc.201300136}
    }
    
    Li hua Wang, Zi zhen Zhang, Cun qin Lv, Bing jun Ding & Yong Guo Large negative differential resistance and rectifying performance modulated by contact sites in fused thiophene trimmer-based molecular devices 2013 Physics Letters A
    Vol. 377(31–33), 1920-1924 
    DOI  
    Abstract: Abstract By applying density functional theory with non-equilibrium Green's function formalism, we have carried out a theoretical study of the electron transport in fused thiophene trimmer-based molecular devices with ethylene connections at three different sites. The simulation results indicate that the electronic transport properties strongly depend on the contact sites. Negative differential resistance and rectifying behaviors occur simultaneously in the current-voltage curves when ethylene connects the fused thiophene trimer at one second-nearest site and one third-nearest site. A larger negative differential resistance occurs only when ethylene connects the fused thiophene trimer at two second-nearest sites.
    Keywords: ATK; Application; molecular device; density functional theory; non-equilibrium Green's function; negative differential resistance; current rectification; transport-properties; 1st-principles; junctions; rectification; conductance; derivatives; geometries; distance; wires
    Area: molecular electronics
    BibTeX:
    @article{Wang2013b,
      author = {Wang, Li-hua and Zhang, Zi-zhen and Lv, Cun-qin and Ding, Bing-jun and Guo, Yong},
      title = {Large negative differential resistance and rectifying performance modulated by contact sites in fused thiophene trimmer-based molecular devices},
      journal = {Physics Letters A},
      year = {2013},
      volume = {377},
      number = {31–33},
      pages = {1920--1924},
      doi = {http://dx.doi.org/10.1016/j.physleta.2013.05.034}
    }
    
    L. Zhu & K.L. Yao Spin transport and magnetic properties of a copper(II) coordination organometallic molecule 2013 Journal of Magnetism and Magnetic Materials
    Vol. 344(0), 14-19 
    DOI  
    Abstract: We study the effects of the characteristics of electrodes and electrode-molecule contacts on the spin-polarized transport properties of a dimeric CuII magnetic single-molecule [Cu2(L1)(hfac)2].·3CH3CN.H2O by density-functional theory (DFT) combined with the Keldysh nonequilibrium Green's-function (NEGF) formalism. It is found that the I-V curve shows negative differential resistance behavior due to the shifting of electrode band structure and the asymmetric coupling between the molecule and the electrodes under bias. In addition, the device presents integrated spintronic functionalities such as switch, spin valve and spin filter, associated with perfect negative magnetoresistance.
    Keywords: ATK; Application; multifunctional molecular device; spin-polarized transport; spintronics; NEGF
    Area: molecular electronics; spin
    BibTeX:
    @article{Zhu2013a,
      author = {Zhu, L. and Yao, K.L.},
      title = {Spin transport and magnetic properties of a copper(II) coordination organometallic molecule},
      journal = {Journal of Magnetism and Magnetic Materials},
      year = {2013},
      volume = {344},
      number = {0},
      pages = {14--19},
      doi = {http://dx.doi.org/10.1016/j.jmmm.2013.04.083}
    }
    
    Anders Blom & Kurt Stokbro Atomistic modeling of semiconductor interfaces 2013 Journal of Computational Electronics
    Vol. 12(4)Journal of Computational Electronics, 623-637 
    DOI  
    Abstract: A strong contributing factor to the success of silicon has been a parallel development of accurate modeling tools. For the efficient introduction of new device architectures at the nanoscale, it is necessary to develop similar tools that can handle all the relevant aspects of the new physical properties that will be utilized. This is a very challenging task, as we are dealing not only with many new materials and even more combinations of elements materials, but also effects due the small device sizes and even reduced dimensionality in the form of confinement. In this article we turn our attention to the topic of simulating interfaces from first principles, on the atomic scale. As device dimensions shrink, interfaces start to play a dominating role, and need to be treated as an active part of the device, and not just as an invisible boundary between different materials. We will review the theoretical framework for computing properties of single interfaces, and provide several examples of the types of simulations that can be performed. A concluding separate section is dedicated to computing band offsets.
    Keywords: ATK; Application; Interfaces; Electron transport; Tunneling; Density functional theory (DFT); Non-equilibrium Green's functions (NEGF); Band offset; Scattering; Transistor; review;
    Area: semi; interfaces
    BibTeX:
    @article{Blom2013,
      author = {Blom, Anders and Stokbro, Kurt},
      title = {Atomistic modeling of semiconductor interfaces},
      booktitle = {Journal of Computational Electronics},
      journal = {Journal of Computational Electronics},
      publisher = {Springer US},
      year = {2013},
      volume = {12},
      number = {4},
      pages = {623-637},
      doi = {http://dx.doi.org/10.1007/s10825-013-0531-2}
    }
    
    Teppei Kato, Shinji Usui & Takahiro Yamamoto Nanostructural Effects on Thermoelectric Power of Graphene Nanoribbons 2013 Japanese Journal of Applied Physics
    Vol. 52, 06GD05 
    DOI URL 
    Abstract: Nanostructural effects on the thermoelectric power of graphene nanoribbons (GNRs) are revealed through first-principles simulation based on the density functional theory combined with nonequilibrium Green's function theory. The thermoelectric power of GNRs exhibits essentially different behavior depending on their edge structure and ribbon width. For zigzag-edged GNRs, the thermoelectric power shows a peculiar energy dependence originating from edge-localized electronic states with energy near the Fermi level. On the other hand, for armchair-edged GNRs (AGNRs), the thermoelectric power is classified into three categories depending on the ribbon width. Among AGNRs with similar ribbon width, an AGNR belonging to a category satisfying mod(Na, 3)=1 displays the largest thermoelectric power, where Na is the integer determining the ribbon width of an AGNR.
    Keywords: ATK; Application; graphene nanoribbon; thermoelectric power
    Area: graphene; thermo
    BibTeX:
    @article{Kato2013,
      author = {Teppei Kato and Shinji Usui and Takahiro Yamamoto},
      title = {Nanostructural Effects on Thermoelectric Power of Graphene Nanoribbons},
      journal = {Japanese Journal of Applied Physics},
      publisher = {The Japan Society of Applied Physics},
      year = {2013},
      volume = {52},
      pages = {06GD05},
      url = {http://jjap.jsap.jp/link?JJAP/52/06GD05/},
      doi = {http://dx.doi.org/10.1143/JJAP.52.06GD05}
    }
    
    Aleksandar Staykov & Petar Tzenov Current Rectification in Mono- and Bilayer Nanographenes with Different Edges 2013 J. Phys. Chem. C
    Vol. 117(26)The Journal of Physical Chemistry C, 13644-13653 
    DOI  
    Abstract: Graphene nanomaterials are actively used in electronics and materials science as elements of electric circuits and both structural and storage components. Their unique structure and electronic properties allow for a wide variety of applications (i.e., electron and thermal conductivity, ion transport, ion storage, and electric-current rectification). In this work, we investigate the electric-current-rectifying properties of mono- and bilayer two-terminal nanographene devices with the nonequilibrium Green's function method combined with density functional theory. The diode-like properties are achieved by control of the nanoribbons' edges. The sequential combination of armchair and zigzag domains leads to nanographene junctions with asymmetric current-voltage characteristics. The rectifying properties of the asymmetric armchair-zigzag carbon materials are derived from the nonequilibrium Green's function theory. The electric-current rectification is explained by the interaction of the external electric field induced between the electrodes with the localized electronic states within the junction. The model is applied on cyclophane molecules and bilayer nanographenes for which one of the layers consists of the armchair-edge nanoribbon, and the second layer consists of the zigzag?edge nanoribbon. Owing to the interlayer pi-pi stacking, the cyclophane and bilayer nanographene junctions show higher rectification ratios compared to the monolayer junctions. The proposed devices consist of nanographenes and polycyclic aromatic hydrocarbons, and the diode-like properties are obtained without heteroatom doping. The investigated carbon materials are promising candidates for current control elements in nanoelectronics.
    Keywords: ATK; Application; bilayer graphene; nanoribbon;
    Area: graphene
    BibTeX:
    @article{Staykov2013,
      author = {Staykov, Aleksandar and Tzenov, Petar},
      title = {Current Rectification in Mono- and Bilayer Nanographenes with Different Edges},
      booktitle = {The Journal of Physical Chemistry C},
      journal = {J. Phys. Chem. C},
      publisher = {American Chemical Society},
      year = {2013},
      volume = {117},
      number = {26},
      pages = {13644--13653},
      doi = {http://dx.doi.org/10.1021/jp402187a}
    }
    
    A. Sengupta, R.K. Ghosh & S. Mahapatra Performance Analysis of Strained Monolayer MoS2 MOSFET 2013 Electron Devices, IEEE Transactions on
    Vol. 60(9)Electron Devices, IEEE Transactions on, 2782-2787 
    DOI  
    Abstract: We present a computational study on the impact of tensile/compressive uniaxial e_xx and biaxial e_xx=e_yy strain on monolayer MoS2, n-, and p-MOSFETs. The material properties like band structure, carrier effective mass, and the multiband Hamiltonian of the channel are evaluated using the density functional theory. Using these parameters, self-consistent Poisson/Schrödinger solution under the nonequilibrium Green's function formalism is carried out to simulate the MOS device characteristics. 1.75% uniaxial tensile strain is found to provide a minor (6%) ON current improvement for the n-MOSFET, whereas same amount of biaxial tensile strain is found to considerably improve the p-MOSFET ON currents by 2-3 times. Compressive strain, however, degrades both n-MOS and p-MOS devices performance. It is also observed that the improvement in p-MOSFET can be attained only when the channel material becomes indirect gap in nature. We further study the performance degradation in the quasi-ballistic long-channel regime using a projected current method.
    Keywords: ATK; Application; effective mass; MOSFET circuits; materials; tensile strain; uniaxial strain, MoS2; density functional theory (DFT); nonequilibrium Green's function (NEGF); strain
    Area: semi, dichalcogenides
    BibTeX:
    @article{Sengupta2013a,
      author = {Sengupta, A. and Ghosh, R.K. and Mahapatra, S.},
      title = {Performance Analysis of Strained Monolayer MoS2 MOSFET},
      booktitle = {Electron Devices, IEEE Transactions on},
      journal = {Electron Devices, IEEE Transactions on},
      year = {2013},
      volume = {60},
      number = {9},
      pages = {2782--2787},
      doi = {http://dx.doi.org/10.1109/TED.2013.2273456}
    }
    
    Serkan Caliskan Tuning the spin dependent behavior of monatomic carbon wires between nickel electrodes 2013 Physics Letters A
    Vol. 377(28-30), 1766-1773 
    DOI  
    Abstract: Abstract Spin polarized Density Functional Theory combined with Non-Equilibrium Green's Function Formalism is applied to investigate the spin dependent transport in carbon based monatomic systems. Both one-dimensional linear and ring structures sandwiched between spin polarized nickel electrodes are examined. Incorporating of nickel electrodes and rings leads to interesting spin dependent properties. The influence of electrode structure is also addressed, using the Ni(100) pyramidal and plane electrodes. It is revealed that spin dependent behavior is largely determined by the atomic arrangement of the monatomic system, and that both the transport and magnetic properties can be tuned by odd/even disparity and/or appropriate ring(s). The mechanisms governing the spin dependent properties in these structures are discussed.
    Keywords: ATK; Application; spin dependent transport; monatomic wires; nickel lead
    Area: molecular electronics; spin
    BibTeX:
    @article{Caliskan2013,
      author = {Caliskan, Serkan},
      title = {Tuning the spin dependent behavior of monatomic carbon wires between nickel electrodes},
      journal = {Physics Letters A},
      year = {2013},
      volume = {377},
      number = {28-30},
      pages = {1766--1773},
      doi = {http://dx.doi.org/10.1016/j.physleta.2013.05.007ggallium}
    }
    
    Can Cao, Ling-Na Chen, Meng-Qiu Long & Hui Xu Rectifying performance in zigzag graphene nanoribbon heterojunctions with different edge hydrogenations 2013 Physics Letters A
    Vol. 377(31-33), 1905-1910 
    DOI  
    Abstract: Using nonequilibrium Green's functions in combination with the density functional theory, we investigated the electronic transport behaviors of zigzag graphene nanoribbon (ZGNR) heterojunctions with different edge hydrogenations. The results show that electronic transport properties of ZGNR heterojunctions can be modulated by hydrogenations, and prominent rectification effects can be observed. We propose that the edge dihydrogenation leads to a blocking of electronic transfer, as well as the changes of the distribution of the frontier orbital at negative/positive bias might be responsible for the rectification effects. These results may be helpful for designing practical devices based on graphene nanoribbons.
    Keywords: ATK; Application; electronic transport property; zigzag graphene nanoribbon heterojunction; edge hydrogenation; rectifying effect
    Area: graphene
    BibTeX:
    @article{Cao2013,
      author = {Cao, Can and Chen, Ling-Na and Long, Meng-Qiu and Xu, Hui},
      title = {Rectifying performance in zigzag graphene nanoribbon heterojunctions with different edge hydrogenations},
      journal = {Physics Letters A},
      year = {2013},
      volume = {377},
      number = {31-33},
      pages = {1905--1910},
      doi = {http://dx.doi.org/10.1016/j.physleta.2013.05.004}
    }
    
    Satyendra Singh Chauhan, Pankaj Srivastava & Ashwani Kumar Shrivastava Electronic and transport properties of boron and nitrogen doped graphene nanoribbons: an ab initio approach 2013 Applied Nanoscience
    Vol. 4Applied Nanoscience, 1-7 
    DOI  
    Abstract: Graphene nanoribbons (GNRs) are expected to display extraordinary properties in the form of nanostructures. The effect of boron and nitrogen substitutional doping at four successive positions on electronic and transport properties of zigzag graphene nanoribbons (ZGNRs) is studied using spin-unpolarized density functional theory. It has been observed that the electronic structures of the doped ZGNRs are different from those of pristine ZGNRs. We have also calculated the transformation energy in the form of total energy. The substitutional boron atom at the nanoribbons edges suppresses the energy band near Fermi level by changing properties of material from metallic to semi-metallic in ZGNRs which can be explained as a consequence of the edge polarization effects. At all doping positions, N-doped ZGNRs are n-type while B-doped ZGNRs are p-type semiconductors. These substitutionally B- and N-doped impurities act as scattering centers for transport in GNRs. Due to unusual properties of these nanomaterials, they can be used in carbon-based nanoelectronics devices.
    Keywords: ATK; Application; graphene nanoribbons; density functional theory; boron; nitrogen; doping
    Area: graphene
    BibTeX:
    @article{Chauhan2013a,
      author = {Chauhan, Satyendra Singh and Srivastava, Pankaj and Shrivastava, Ashwani Kumar},
      title = {Electronic and transport properties of boron and nitrogen doped graphene nanoribbons: an ab initio approach},
      booktitle = {Applied Nanoscience},
      journal = {Applied Nanoscience},
      publisher = {Springer-Verlag},
      year = {2013},
      volume = {4},
      pages = {1-7},
      doi = {http://dx.doi.org/10.1007/s13204-013-0220-2}
    }
    
    R.M. Hariharan & D. John Thiruvadigal Effect of anchoring atoms on transport properties of a carbon-dimer based molecular junctions: a first principles study 2013 Nanosystems: Physics, Chemistry, Mathematics
    Vol. 4(2), 294-298 
    URL 
    Abstract: The conductance of a molecular device is sensitive to the contact geometry between the molecules and the probing electrodes. Combining the density functional theory calculations (DFT) for molecular electronic structure with a non-equilibrium Green's function (NEGF) method for electron transport, we calculate the molecular conductance of carbon dimer connected between Au leads through two different anchoring atoms Se and Te. The current-voltage characteristics and transmission spectra of two systems are studied. The results exhibit that, depending on the anchoring groups and the subsequent different metal-molecule chemical bonds, the current varies over more than four times of magnitude under the same bias. Furthermore, the system exhibits negative differential resistance (NDR) effect, when anchored with Te atom. This emphasizes the great importance of the anchoring groups in molecular devices.
    Keywords: ATK; Application; molecular electronics; anchoring group effects; electronic transport; first-principle; I-V characteristics
    Area: molecular electronics
    BibTeX:
    @article{Hariharan2013,
      author = {R. M. Hariharan and D. John Thiruvadigal},
      title = {Effect of anchoring atoms on transport properties of a carbon-dimer based molecular junctions: a first principles study},
      journal = {Nanosystems: Physics, Chemistry, Mathematics},
      year = {2013},
      volume = {4},
      number = {2},
      pages = {294-298},
      url = {http://nanojournal.ifmo.ru/articles/volume4/4-2/mam-12/paper17/}
    }
    
    C. Preferencial Kala, P. Aruna Priya & D. John Thiruvadigal Investigation of Terminal Group Effect on Electron Transport Through Open Molecular Structures 2013 Communications in Theoretical Physics
    Vol. 59(5), 649-654 
    DOI  
    Abstract: The effect of terminal groups on the electron transport through metal-molecule-metal system has been investigated using nonequilibrium Green's function (NEGF) formalism combined with extended Huckel theory (EHT). Au-molecule-Au junctions are constructed with borazine and BCN unit structure as core molecule and sulphur (S), oxygen (O), selenium (Se) and cyano-group (CN) as terminal groups. The electron transport characteristics of the borazine and BCN molecular systems are analyzed through the transmission spectra and the current-voltage curve. The results demonstrate that the terminal groups modifying the transport behaviors of these systems in a controlled way. Our result shows that, selenium is the best linker to couple borazine to Au electrode and oxygen is the best one to couple BCN to Au electrode. Furthermore, the results of borazine systems are compared with that of BCN molecular systems and are discussed. Simulation results show that the conductance through BCN molecular systems is four times larger than the borazine molecular systems. Negative differential resistance behavior is observed with borazine-CN system and the saturation feature appears in BCN systems.
    Keywords: ATK-SE; Application; molecular electronics; extended Huckel theory (EHT); nonequilibrium Green's function (NEGF); quantum transport
    Area: molecular electronics
    BibTeX:
    @article{Kala2013,
      author = {C. Preferencial Kala and P. Aruna Priya and D. John Thiruvadigal},
      title = {Investigation of Terminal Group Effect on Electron Transport Through Open Molecular Structures},
      journal = {Communications in Theoretical Physics},
      year = {2013},
      volume = {59},
      number = {5},
      pages = {649-654},
      doi = {http://dx.doi.org/10.1088/0253-6102/59/5/21}
    }
    
    Manabu Kiguchi, Junichi Inatomi, Yuuta Takahashi, Ryota Tanaka, Takafumi Osuga, Takashi Murase, Makoto Fujita, Tomofumi Tada & Satoshi Watanabe Highly Conductive [3 x n] Gold-Ion Clusters Enclosed within Self-Assembled Cages 2013 Angew. Chem. Int. Ed.
    Vol. 52(24), 6202-6205 
    DOI  
    Keywords: ATK; Application; cluster compounds; electron transfer; gold; molecular electronics; single-molecule studies
    Area: molecular electronics
    BibTeX:
    @article{Kiguchi2013,
      author = {Kiguchi, Manabu and Inatomi, Junichi and Takahashi, Yuuta and Tanaka, Ryota and Osuga, Takafumi and Murase, Takashi and Fujita, Makoto and Tada, Tomofumi and Watanabe, Satoshi},
      title = {Highly Conductive [3 x n] Gold-Ion Clusters Enclosed within Self-Assembled Cages},
      journal = {Angew. Chem. Int. Ed.},
      publisher = {WILEY-VCH Verlag},
      year = {2013},
      volume = {52},
      number = {24},
      pages = {6202--6205},
      doi = {http://dx.doi.org/10.1002/anie.201301665}
    }
    
    Vijay K. Lamba & O.P. Garg Modelling of Junctions between ZnO Rods/Nano Ribbons and Gold Electrodes 2012 Journal of Environmental Science, Computer Science and Engineering and Technology
    Vol. 1(3), 499 
    URL 
    Abstract: Using first-principles density functional theory calculations, various junction smodels constructed from different ZnO structures (i.e. rods & nano ribbons) and Gold electrodes/films units via covalent linkage have been envisioned. These models consist of linear, T, H, and L-shaped junctions within the connection modes between ZnO structures (i.e. rods & nano ribbons) and Gold electrodes/films units. The transport properties of the designed junctions were calculated with Atomistix Toolkit which is based on the combination of DFT with the non-equilibrium Green's function (NEGF) formalism. The NEGF-DFT approach has now become standard and is utilized extensively to describe and predict the behavior of different molecular junctions. The NEGF formulation has an inherent elegance and generality, which makes it an attractive way to approach these issues. The simulation procedure is as follows: the self-consistent potential of two electrodes is calculated first, which will be shifted strictly with each other by external bias. Then, the electron density of the central scattering region is obtained from the Green's function. When the electron density is known, the DFT Hamiltonian matrix can be computed using boundary conditions. This procedure is iterated until self-consistency is achieved. The simulation results obtained for geometrical properties, binding effects, Linear, T, H, and L shaped metal-metal junctions, and Linear, T, H, and L shaped metalsemiconductor junctions suggested that the proposed models are promising for future applications in designing and fabrication of nano generator using ZnO rods.
    Keywords: ATK; Application; nanowire; junctions; NEGF; DFT; Two Probe Systems
    Area: nanowires
    BibTeX:
    @article{Lamba2012a,
      author = {Vijay K. Lamba and O. P. Garg},
      title = {Modelling of Junctions between ZnO Rods/Nano Ribbons and Gold Electrodes},
      journal = {Journal of Environmental Science, Computer Science and Engineering and Technology},
      year = {2012},
      volume = {1},
      number = {3},
      pages = {499},
      url = {http://www.jecet.org/}
    }
    
    Zheng Li, Jiaxin Zheng, Zeyuan Ni, Ruge Quhe, Yangyang Wang, Zhengxiang Gao & Jing Lu Intrinsic region length scaling of heavily doped carbon nanotube p-i-n junctions 2013 Nanoscale
    Vol. 5(15), 6999-7004 
    DOI  
    Abstract: We investigated the dependence of the transport properties of heavily doped intratube single-walled carbon nanotube (SWCNT) p-i-n junctions on the length of the intrinsic region by using empirical self-consistent quantum transport simulations. When the length of the intrinsic region is scaled from a few angstroms to over 10 nanometers, the SWCNT p-i-n junction evolves from a tunneling diode with a large negative rectification and large negative differential resistance to one with a large positive rectification (like a conventional positive rectifying diode). The critical length of the intrinsic length is about 8.0 nm. Therefore, one can obtain nanoscale diodes of different performance types by changing the intrinsic region length.
    Keywords: ATK; Application; nanotube; doping; rectification; field-effect transistors; thin insulating film; rectification; formula; diodes
    Area: nanotubes
    BibTeX:
    @article{Li2013b,
      author = {Li, Zheng and Zheng, Jiaxin and Ni, Zeyuan and Quhe, Ruge and Wang, Yangyang and Gao, Zhengxiang and Lu, Jing},
      title = {Intrinsic region length scaling of heavily doped carbon nanotube p-i-n junctions},
      journal = {Nanoscale},
      publisher = {The Royal Society of Chemistry},
      year = {2013},
      volume = {5},
      number = {15},
      pages = {6999--7004},
      doi = {http://dx.doi.org/10.1039/C3NR01462B}
    }
    
    J. Li, Z.H. Zhang, G. Kwong, W. Tian, Z.Q. Fan & X.Q. Deng A new exploration on the substantial improvement of rectifying behaviors for a donor-acceptor molecular diode by graphene electrodes 2013 Carbon
    Vol. 61(0), 284-293 
    DOI  
    Abstract: Sandwiching a donor-acceptor molecule between two graphene nanoribbon (GNR) electrodes to construct a particular molecular diode, our calculations from the first-principles method predict that such a configuration can lead to dramatically different and unexpected effects. When the GNR electrodes are semiconducting, the rectifying behaviors for this molecule can be enhanced greatly. The maximum rectification ratio rises sharply with an increase of the bandgap size of GNR electrodes and can reach a value more than 4000 as the bandgap is about 0.8 eV, which is of a very significant improvement as compared with previously investigated results for such a molecule coupled to bulk metal electrodes. Therefore, our studies imply that using graphene with a large bandgap as electrodes might be a novel effective pathway to greatly raise rectifying behaviors of a donor-acceptor molecule.
    Keywords: ATK; Application; graphene nanoribbon; doping; rectification; diode; transport properties; room-temperature
    Area: graphene
    BibTeX:
    @article{Li2013c,
      author = {Li, J. and Zhang, Z.H. and Kwong, G. and Tian, W. and Fan, Z.Q. and Deng, X.Q.},
      title = {A new exploration on the substantial improvement of rectifying behaviors for a donor-acceptor molecular diode by graphene electrodes},
      journal = {Carbon},
      year = {2013},
      volume = {61},
      number = {0},
      pages = {284--293},
      doi = {http://dx.doi.org/10.1016/j.carbon.2013.05.006}
    }
    
    Amretashis Sengupta & Santanu Mahapatra Performance limits of transition metal dichalcogenide (MX[sub 2]) nanotube surround gate ballistic field effect transistors 2013 Journal of Applied Physics
    Vol. 113(19), 194502 
    DOI  
    Abstract: We theoretically analyze the performance of transition metal dichalcogenide (MX2) single wall nanotube (SWNT) surround gate MOSFET, in the 10 nm technology node. We consider semiconducting armchair (n, n) SWNT of MoS2, MoSe2, WS2, and WSe2 for our study. The material properties of the nanotubes are evaluated from the density functional theory, and the ballistic device characteristics are obtained by self-consistently solving the Poisson-Schrödinger equation under the non-equilibrium Green's function formalism. Simulated ON currents are in the range of 61-76 muA for 4.5 nm diameter MX2 tubes, with peak transconductance 175-218 muS and ON/OFF ratio 0.6e-5 to 0.8e-5. The subthreshold slope is 62.22 mV/decade and a nominal drain induced barrier lowering of 12-15 mV/V is observed for the devices. The tungsten dichalcogenide nanotubes offer superior device output characteristics compared to the molybdenum dichalcogenide nanotubes, with WSe2 showing the best performance. Studying SWNT diameters of 2.5-5 nm, it is found that increase in diameter provides smaller carrier effective mass and 4%-6% higher ON currents. Using mean free path calculation to project the quasi-ballistic currents, 62%-75% reduction from ballistic values in drain current in long channel lengths of 100, 200 nm is observed.
    Keywords: ATK; Application; dichalcogenides; nanotube; field effect transistor; gate all around;s
    Area: nanotubes; dichalcogenides
    BibTeX:
    @article{Sengupta2013,
      author = {Sengupta, Amretashis and Mahapatra, Santanu},
      title = {Performance limits of transition metal dichalcogenide (MX[sub 2]) nanotube surround gate ballistic field effect transistors},
      journal = {Journal of Applied Physics},
      publisher = {AIP},
      year = {2013},
      volume = {113},
      number = {19},
      pages = {194502},
      doi = {http://dx.doi.org/10.1063/1.4805059}
    }
    
    Anurag Srivastava, Noopur Jain & A.K. Nagawat Effect of Stone-Wales Defects on Electronic Properties of CNTs: Ab-Initio Study 2013 Quantum Matter
    Vol. 2(4), 307-313 
    DOI URL 
    Abstract: Present paper discusses the ab-initio > analysis of electronic properties of zigzag carbon nanotubes (CNTs) on increasing the number of Stone-Wales (SW) defects. Computation has been performed by using local density approximation (LDA) under Perdew-Zunger (PZ) parameterization as exchange correlation functional. Analysis depicts an interesting variation in band gap with increase in number of SW defects introduced in zigzag CNTs with n = 7, 8, and 9. The comparative band gap progression with number of SW defects in the three nanotubes have also been analyzed and discussed in detail.
    Keywords: ATK; Application; electronic properties; ab-initio; carbon nanotube; CNT; Stone-Wales defects
    Area: nanotubes
    BibTeX:
    @article{Srivastava2013a,
      author = {Srivastava, Anurag and Jain, Noopur and Nagawat, A.K.},
      title = {Effect of Stone-Wales Defects on Electronic Properties of CNTs: Ab-Initio Study},
      journal = {Quantum Matter},
      year = {2013},
      volume = {2},
      number = {4},
      pages = {307--313},
      url = {Google confirms ATK},
      doi = {http://dx.doi.org/10.1166/qm.2013.1061}
    }
    
    G.P. Tang, J.C. Zhou, Z.H. Zhang, X.Q. Deng & Z.Q. Fan A theoretical investigation on the possible improvement of spin-filter effects by an electric field for a zigzag graphene nanoribbon with a line defect 2013 Carbon
    Vol. 60(0), 94-101 
    DOI  
    Abstract: The spin-polarized electronic properties for a zigzag-edge graphene nanoribbon (ZGNR) with an extended line defect are investigated, particularly focusing on controlling the effects of an external transverse electric field (Eext). An ab initio scanning tunneling microscope image for the defective ZGNR is also predicted. Results show that such a ZGNR can exhibit a strong spin polarization and ferromagnetic state, and the spin-filter effect can be significantly tuned and improved by the Eext. The spin-filter efficiency for our proposed device is predicted to be able to reach up to 60-81% in a large bias range of 0-0.6 V at Eext = 3.0 V/nm. Mechanisms for such results and the experimental feasibility for the device are suggested. These findings suggest a new possibility for developing nanometer-scale all-carbon spintronic devices.
    Keywords: ATK; Application; graphene; defect; spin filter; spintronics
    Area: graphene; spin
    BibTeX:
    @article{Tang2013,
      author = {Tang, G.P. and Zhou, J.C. and Zhang, Z.H. and Deng, X.Q. and Fan, Z.Q.},
      title = {A theoretical investigation on the possible improvement of spin-filter effects by an electric field for a zigzag graphene nanoribbon with a line defect},
      journal = {Carbon},
      year = {2013},
      volume = {60},
      number = {0},
      pages = {94--101},
      doi = {http://dx.doi.org/10.1016/j.carbon.2013.04.002}
    }
    
    Mayank Chakraverty & Harish M. Kittur First Principle Simulations of Fe/MgO/Fe Magnetic Tunnel Junctions for Applications in Magnetoresistive Random Access Memory Based Cell Phone Architectures 2011 International Journal of Micro and Nano Systems
    Vol. 2(1), 1-6 
    URL 
    Abstract: Fe/MgO/Fe magnetic tunnel junctions (MTJs) have been reported to have very high tunnel magnetoresistance (TMR) ratios. In this work, we present the results of First Principle simulations of Fe/MgO/Fe MTJs with LSDA as the exchange correlation. The I-V characteristics in the antiparallel magnetization state exhibit strong features. The bias dependence of the TMR ratio shows nearly 100% TMR ratios for bias voltages up to 1.5 Volts. The MgO thickness dependence of the tunnel resistance shows the expected exponential increase in the tunnel resistance. The write energy per bit and power consumption have been computed for a bias voltage of 0.5 Volts. The Fe/MgO/Fe MTJs are the most widely used MTJs, integrated with NMOS transistors, in the form of MTJ based Magnetoresistive Random Access Memory (MRAM) which is an advanced memory technology operating at the nano scale. MRAMs are spintronic devices.
    Keywords: ATK; Application; spin; first Principle; LSDA; MTJ; TMR
    Area: interfaces; nvm; spin
    BibTeX:
    @article{Chakraverty2011,
      author = {Mayank Chakraverty and Harish M. Kittur},
      title = {First Principle Simulations of Fe/MgO/Fe Magnetic Tunnel Junctions for Applications in Magnetoresistive Random Access Memory Based Cell Phone Architectures},
      journal = {International Journal of Micro and Nano Systems},
      year = {2011},
      volume = {2},
      number = {1},
      pages = {1-6},
      url = {http://www.serialsjournals.com/articles.php?volumesno_id=276&journals_id=148&volumes_id=461}
    }
    
    Mayank Chakraverty & Harish M. Kittur First Principle Study of Tunnel Currents through CeO2, Y2O3, TiO2 and Al2O3 Dielectrics in MOSFETs for Ultra Large Scale Integration 2012 Advanced Materials Research
    Vol. 584, 428-432 
    DOI  
    Abstract: High gate leakage current, as a central problem, has decelerated the downscaling of minimum feature size of the field effect transistors In this paper, a combination of density functional theory and non equilibrium Green's function formalism has been applied to the atomic scale calculation of the tunnel currents through CeO2, Y2O3, TiO2 and Al2O3 dielectrics in MOSFETs. The tunnel currents for different bias voltages applied to Si/Insulator/Si systems have been obtained along with tunnel conductance v/s bias voltage plots for each system. The results are in agreement to the use of high dielectric constant materials as gate dielectric so as to enable further downscaling of MOSFETs with reduced gate leakage currents thereby enabling ultra large scale integration. When used as dielectric, TiO2 exhibits extremely low tunnel currents followed by Y2O3 while CeO2 and Al2O3 exhibit high tunnel currents through them at certain bias voltages.
    Keywords: ATK; Application; CMOS; FIBL; leakage current; MOSFET; threshold voltage; ULSI
    Area: interfaces; semi
    BibTeX:
    @article{Chakraverty2012a,
      author = {Mayank Chakraverty and Harish M. Kittur},
      title = {First Principle Study of Tunnel Currents through CeO2, Y2O3, TiO2 and Al2O3 Dielectrics in MOSFETs for Ultra Large Scale Integration},
      journal = {Advanced Materials Research},
      year = {2012},
      volume = {584},
      pages = {428-432},
      doi = {http://dx.doi.org/10.4028/www.scientific.net/AMR.584.428}
    }
    
    Mayank Chakraverty, P. Arun Kumar & Harish M Kittur Performance Analysis of Fe/SiO2/Fe MTJ and Ni/Al2O3/Ni MTJ based Magnetoresistive Random Access Memories 2012 Journal of VLSI Design Tools & Technology
    Vol. 2(2), 1 
    URL 
    Abstract: This paper reports the first principle simulations of Fe/SiO2/Fe and Ni/Al2O3/Ni magnetic tunnel junctions (MTJs). A performance analysis has been done based upon the device-level simulations of the two magnetic tunnel junctions followed by the circuit level simulations of magnetoresistive random access memory (MRAM) cell operating with the two MTJs respectively. From the device-level simulations, the two MTJs have been compared with regard to the bias dependence of TMR ratios, insulator thickness dependence of TMR ratios and insulator thickness dependence of parallel and anti-parallel state resistances taking the relative magnetizations of the two ferromagnetic films of the MTJs into consideration. From the circuit-level simulations, the static and switching power dissipations have been computed along with the delay time estimation.
    Keywords: ATK; Application; MTJ; spin;
    Area: interfaces; nvm; spin
    BibTeX:
    @article{Chakraverty2012b,
      author = {Mayank Chakraverty and P. Arun Kumar and Harish M Kittur},
      title = {Performance Analysis of Fe/SiO2/Fe MTJ and Ni/Al2O3/Ni MTJ based Magnetoresistive Random Access Memories},
      journal = {Journal of VLSI Design Tools & Technology},
      year = {2012},
      volume = {2},
      number = {2},
      pages = {1},
      url = {http://www.stmjournals.com/index.php?journal=JoVDTT&page=article&op=view&path[]=2244}
    }
    
    Mayank Chakraverty & Harish M Kittur Comparison of tunnel currents through SiO2, HfO2, Ta2O5, ZrO2 and Dy2O3 dielectrics in MOS devices for ultra large scale integration using first principle calculations 2013 Emerging Research Areas and 2013 International Conference on Microelectronics, Communications and Renewable Energy (AICERA/ICMiCR), 2013 Annual International Conference on, 1-6  DOI  
    Abstract: The work presented in this paper focuses on the effects of high leakage current in field effect transistors and the possible ways to play down with the leakage currents. This paper combines density functional theory and non equilibrium Green's function formalism to perform atomic scale calculation of tunnel currents through SiO2, HfO2, Ta2O5ZrO2 and DY2O3 dielectrics in MOSFETs. The tunnel currents for different bias voltages applied to Si/Insulator/Si systems have been obtained along with tunnel conductance v/s bias voltage plots for each system and the plots have been analyzed with reference to the presently used bulk Si/SiO2/Si systems that have SiO2 as the gate dielectric material. The results justify the use of high dielectric constant materials as gate dielectric in FET devices so as to enable further downscaling of MOSFETs with reduced gate leakage currents thereby enabling ultra large scale integration.
    Keywords: ATK; Application; dielectrics; insulators; leakage currents; logic gates;MOSFET;Silicon;CMOS;Gate Leakage current;MOSFETS;drive current;threshold voltage;transconductance;tunnel current
    Area: interfaces; semi
    BibTeX:
    @inproceedings{Chakraverty2013,
      author = {Chakraverty, Mayank and Kittur, Harish M},
      title = {Comparison of tunnel currents through SiO2, HfO2, Ta2O5, ZrO2 and Dy2O3 dielectrics in MOS devices for ultra large scale integration using first principle calculations},
      booktitle = {Emerging Research Areas and 2013 International Conference on Microelectronics, Communications and Renewable Energy (AICERA/ICMiCR), 2013 Annual International Conference on},
      year = {2013},
      pages = {1-6},
      doi = {http://dx.doi.org/10.1109/AICERA-ICMiCR.2013.6575936}
    }
    
    Wei Liu, Jiahao Kang, Deblina Sarkar, Yasin Khatami, Debdeep Jena & Kaustav Banerjee Role of Metal Contacts in Designing High-Performance Monolayer n-Type WSe2 Field Effect Transistors 2013 Nano Lett.
    Vol. 13(5)Nano Letters, 1983-1990 
    DOI  
    Abstract: This work presents a systematic study toward the design and first demonstration of high-performance n-type monolayer tungsten diselenide (WSe2) field effect transistors (FET) by selecting the contact metal based on understanding the physics of contact between metal and monolayer WSe2. Device measurements supported by ab initio density functional theory (DFT) calculations indicate that the d-orbitals of the contact metal play a key role in forming low resistance ohmic contacts with monolayer WSe2. On the basis of this understanding, indium (In) leads to small ohmic contact resistance with WSe2 and consequently, back-gated In-WSe2 FETs attained a record ON-current of 210 microA/micrometer, which is the highest value achieved in any monolayer transition-metal dichalcogenide- (TMD) based FET to date. An electron mobility of 142 cm2/Vs (with an ON/OFF current ratio exceeding 10^6) is also achieved with In-WSe2 FETs at room temperature. This is the highest electron mobility reported for any back gated monolayer TMD material till date. The performance of n-type monolayer WSe2 FET was further improved by Al2O3 deposition on top of WSe2 to suppress the Coulomb scattering. Under the high-k dielectric environment, electron mobility of Ag-WSe2 FET reached ~202 cm2/Vs with an ON/OFF ratio of over 10^6 and a high ON-current of 205 microA/micrometer. In tandem with a recent report of p-type monolayer WSe2 FET (Fang, H. et al. Nano Lett. 2012, 12, (7), 3788-3792), this demonstration of a high-performance n-type monolayer WSe2 FET corroborates the superb potential of WSe2 for complementary digital logic applications.
    Keywords: ATK; Application; 2D semiconductors; contact resistance; field-effect-transistor; monolayer; transition-metal dichalcogenides; tungsten diselenide; WSe2
    Area: graphene, interfaces, dichalcogenides
    BibTeX:
    @article{Liu2013b,
      author = {Liu, Wei and Kang, Jiahao and Sarkar, Deblina and Khatami, Yasin and Jena, Debdeep and Banerjee, Kaustav},
      title = {Role of Metal Contacts in Designing High-Performance Monolayer n-Type WSe2 Field Effect Transistors},
      booktitle = {Nano Letters},
      journal = {Nano Lett.},
      publisher = {American Chemical Society},
      year = {2013},
      volume = {13},
      number = {5},
      pages = {1983--1990},
      doi = {http://dx.doi.org/10.1021/nl304777e}
    }
    
    Yun Ni, Kai-Lun Yao, Hua-Hua Fu, Guo-Ying Gao, Si-Cong Zhu, Bo Luo, Shu-Ling Wang & Rui-Xue Li The transport properties and new device design: the case of 6,6,12-graphyne nanoribbons 2013 Nanoscale
    Vol. 5(10), 4468-4475 
    DOI  
    Abstract: By performing first-principle quantum transport calculations, we studied the transport properties of three kinds of 6,6,12-graphyne nanoribbons with different edges and different cutting directions. The nanoribbon with zigzag edges shows metallic properties and the spin-polarized currents show an obvious negative differential resistance effect, the other two nanoribbons terminated by a phenyl ring are semiconductors and spin-unpolarized. We also designed several nanowire devices based on these 6,6,12-graphyne nanoribbons, such as rectifier, spin filter diode, spin FET and spin caloritronics devices. These results indicate that 6,6,12-graphyne is a potential candidate for spintronics and spin caloritronics.
    Keywords: ATK; Application; spin; graphene; graphyne nanoribbon; spintronics; caloritronics; negative differential resistance; NDR;
    Area: graphene; spin; thermo
    BibTeX:
    @article{Ni2013a,
      author = {Ni, Yun and Yao, Kai-Lun and Fu, Hua-Hua and Gao, Guo-Ying and Zhu, Si-Cong and Luo, Bo and Wang, Shu-Ling and Li, Rui-Xue},
      title = {The transport properties and new device design: the case of 6,6,12-graphyne nanoribbons},
      journal = {Nanoscale},
      publisher = {The Royal Society of Chemistry},
      year = {2013},
      volume = {5},
      number = {10},
      pages = {4468--4475},
      doi = {http://dx.doi.org/10.1039/C3NR00731F}
    }
    
    Zhenhua Zhang, Chao Guo, Denise Jeng Kwong, Jie Li, Xiaoqing Deng & Zhiqiang Fan A Dramatic Odd-Even Oscillating Behavior for the Current Rectification and Negative Differential Resistance in Carbon-Chain-Modified Donor-Acceptor Molecular Devices 2013 Advanced Functional Materials
    Vol. 23(21), 2765-2774 
    DOI  
    Abstract: The donor-acceptor molecule is the only molecule that features a real intrinsic rectification. However, all investigations in the last decades showed that rectification behaviors of such molecules are not promising since their rectification ratio is only on the order of 10. Use of carbon chains C_n to serve as spacers is reported, along with attempts to modulate electrical behavior of the donor-acceptor molecule. Calculations using the first-principles method show that electrical behavior is indeed altered substantively, and a particular regularity can be clearly observed, i.e., a dramatic odd-even oscillation for electronic behavior with increasing carbon-chain length n. For models with even-n carbon chains, the rectification ratio is small (30), and no negative differential resistance (NDR) behavior is detected, but the rectifying performance of models with odd-n carbon chains is tremendously improved and rectification ratios on the order of 50 to 400 can be achieved, alongside a large NDR. This study thus suggests that using a suitable spacer might be an effective way to significantly boost electrical characteristics, including rectifying performance, of the donor-acceptor molecule.
    Keywords: ATK; Application; molecular electronics; donor-acceptor molecule: negative differential resistance; NDR; molecular devices; carbon chains; rectification behavior;
    Area: molecular electronics
    BibTeX:
    @article{Zhang2013a,
      author = {Zhang, Zhenhua and Guo, Chao and Kwong, Denise Jeng and Li, Jie and Deng, Xiaoqing and Fan, Zhiqiang},
      title = {A Dramatic Odd-Even Oscillating Behavior for the Current Rectification and Negative Differential Resistance in Carbon-Chain-Modified Donor-Acceptor Molecular Devices},
      journal = {Advanced Functional Materials},
      year = {2013},
      volume = {23},
      number = {21},
      pages = {2765--2774},
      doi = {http://dx.doi.org/10.1002/adfm.201201790}
    }
    
    Andreas Zienert, Jörg Schuster & Thomas Gessner Extended Hückel Theory for Carbon Nanotubes: Band Structure and Transport Properties 2013 J. Phys. Chem. A
    Vol. 117(17)The Journal of Physical Chemistry A, 3650-3654 
    DOI  
    Abstract: Extended Hückel theory (EHT) is a well established method for the description of the electronic structure of molecules and solids. In this article, we present a set of extended Hückel parameters for carbon nanotubes (CNTs), obtained by fitting the ab initio band structure of the (6,0) CNT. The new parameters are highly transferable to different types of CNTs. To demonstrate the versatility of the approach, we perform self-consistent EHT-based electron transport calculations for finite length CNTs with metal electrodes.
    Keywords: ATK-SE; Application; carbon nanotube; NEGF; pseudopotentials; interconnect; transistor; sensors; gaps
    Area: nanotubes
    BibTeX:
    @article{Zienert2013,
      author = {Zienert, Andreas and Schuster, Jörg and Gessner, Thomas},
      title = {Extended Hückel Theory for Carbon Nanotubes: Band Structure and Transport Properties},
      booktitle = {The Journal of Physical Chemistry A},
      journal = {J. Phys. Chem. A},
      publisher = {American Chemical Society},
      year = {2013},
      volume = {117},
      number = {17},
      pages = {3650--3654},
      doi = {http://dx.doi.org/10.1021/jp312586j}
    }
    
    Somobrata Acharya, Bidisa Das, Umamahesh Thupakula, Katsuhiko Ariga, D.D. Sarma, Jacob Israelachvili & Yuval Golan A Bottom-Up Approach toward Fabrication of Ultrathin PbS Sheets 2013 Nano Lett.
    Vol. 13(2)Nano Letters, 409-415 
    DOI  
    Abstract: Two-dimensional (2D) sheets are currently in the spotlight of nanotechnology owing to high-performance device fabrication possibilities. Building a free-standing quantum sheet with controlled morphology is challenging when large planar geometry and ultranarrow thickness are simultaneously concerned. Coalescence of nanowires into large single-crystalline sheet is a promising approach leading to large, molecularly thick 2D sheets with controlled planar morphology. Here we report on a bottom-up approach to fabricate high-quality ultrathin 2D single crystalline sheets with well-defined rectangular morphology via collective coalescence of PbS nanowires. The ultrathin sheets are strictly rectangular with 1.8 nm thickness, 200-250 nm width, and 3-20 micrometer length. The sheets show high electrical conductivity at room and cryogenic temperatures upon device fabrication. Density functional theory (DFT) calculations reveal that a single row of delocalized orbitals of a nanowire is gradually converted into several parallel conduction channels upon sheet formation, which enable superior in-plane carrier conduction.
    Keywords: ATK; Application; nanowires; ultrathin sheet; coalescence; activation energy; DFT calculations; transport; metal-insulator-transition; Langmuir monolayers; ballistic transport; oriented attachment; suspended graphene; room-temperature; nanowires; superlattices; nanocrystals
    Area: nanowires
    BibTeX:
    @article{Acharya2013,
      author = {Acharya, Somobrata and Das, Bidisa and Thupakula, Umamahesh and Ariga, Katsuhiko and Sarma, D. D. and Israelachvili, Jacob and Golan, Yuval},
      title = {A Bottom-Up Approach toward Fabrication of Ultrathin PbS Sheets},
      booktitle = {Nano Letters},
      journal = {Nano Lett.},
      publisher = {American Chemical Society},
      year = {2013},
      volume = {13},
      number = {2},
      pages = {409--415},
      doi = {http://dx.doi.org/10.1021/nl303568d}
    }
    
    Zhaoqiang Bai, Yongqing Cai, Lei Shen, Guchang Han & Yuanping Feng High-performance giant-magnetoresistance junctions based on the all-Heusler architecture with matched energy bands and Fermi surfaces 2013 Applied Physics Letters
    Vol. 102(15), 152403 
    DOI  
    Abstract: We present an all-Heusler architecture which could be used as a rational design scheme for achieving high spin-filter efficiency in the current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) devices. A Co2MnSi/Ni2NiSi/Co2MnSi trilayer stack is chosen as the prototype of such an architecture, of which the electronic structure and magnetotransport properties are systematically investigated by first principles approaches. Well matched energy bands and Fermi surfaces between the all-Heusler electrode-spacer pair are found, which, in combination with the electrode half-metallicity, indicate large bulk and interfacial spin-asymmetry, high spin-filter efficiency, and consequently good magnetoresistance performance. Transport calculations further confirm the superiority of the all-Heusler architecture over the conventional Heusler/transition-metal structure by comparing their transmission coefficients and interfacial resistances of parallel conduction electrons, as well as the macroscopic current-voltage characteristics. We suggest future theoretical and experimental efforts in developing high-performance all-Heusler CPP-GMR junctions for the read heads of the next generation high-density hard disk drives.
    Keywords: ATK; Application; interfaces; spin; semi; ab initio calculations, band structure, cobalt alloys, Fermi surface, giant magnetoresistance, manganese alloys, multilayers, nickel alloys, silicon alloys, spin systems
    Area: interfaces; spin; semi; nvm
    BibTeX:
    @article{Bai2013a,
      author = {Bai, Zhaoqiang and Cai, Yongqing and Shen, Lei and Han, Guchang and Feng, Yuanping},
      title = {High-performance giant-magnetoresistance junctions based on the all-Heusler architecture with matched energy bands and Fermi surfaces},
      journal = {Applied Physics Letters},
      publisher = {AIP},
      year = {2013},
      volume = {102},
      number = {15},
      pages = {152403},
      doi = {http://dx.doi.org/10.1063/1.4802581}
    }
    
    S. Barzilai, F. Tavazza & L.E. Levine First-principle modeling of gold adsorption on BeO (0001) 2013 Surface Science
    Vol. 609(0), 39-43 
    DOI  
    Abstract: Gold nanowire chains are considered a good candidate for nanoelectronic devices since they exhibit remarkable structural and electrical properties. For practical engineering devices, alpha-wurtzite BeO may be a useful platform for supporting these nanowires, since the atom separation of the BeO (0001) surface is compatible with the Au-Au atom spacing. However, its influence on the nanowire conductivity is unknown. Here, ab initio simulations of adsorption of one gold atom on cleaved BeO (0001) surfaces have been performed to find the most favorable adsorption site. An attractive adsorption was obtained for all the studied sites, but the most favorable site was above the oxygen for the O-terminated surface and above the Be-Be bridge for the Be-terminated surface. A relatively high electron density is observed in the AuO and AuBe bonds, and the local density of states exhibits high peaks in the vicinity of the Fermi energy.
    Keywords: ATK; Application; BeO; ab-initio calculations, adsorption, substrate; geometry optimization; band-structure; surfaces; conductance; molecules; chains; oxide
    Area: nanowires
    BibTeX:
    @article{Barzilai2013a,
      author = {Barzilai, S. and Tavazza, F. and Levine, L.E.},
      title = {First-principle modeling of gold adsorption on BeO (0001)},
      journal = {Surface Science},
      year = {2013},
      volume = {609},
      number = {0},
      pages = {39--43},
      doi = {http://dx.doi.org/10.1016/j.susc.2012.10.017}
    }
    
    Nikolai Lebedev, Igor Griva & Anders Blom Internal Control of Electron Transfer through a Single Iron Atom by Chelating Porphyrin 2013 J. Phys. Chem. C
    Vol. 117(14)The Journal of Physical Chemistry C, 6933-6939 
    DOI  
    Abstract: Construction of efficient and highly integrated electronic devices is the main challenge and goal of nanoelectronics. The main problem in the construction of such devices is the fusion between conducting and controlling parts of the device, substantially reducing the efficiency of regulation. To approach the problem we study the electron transfer through a carbon nanotube (CNT)-histidine-heme-histidine-CNT conjugate with an orthogonal porphyrin orientation relative to the CNT electrodes. Using density functional theory and nonequilibrium Green's function calculations we show that at low bias the CNT molecular orbitals are electronically coupled only to the Fe atom but uncoupled from the tetrapyrrole ring of the porphyrin. We found that at low bias the electrons pass exclusively through the central Fe atom of the porphyrin, but at higher bias they are partially scattered by the tetrapyrrole ring, leading to a reduction of the total current through the molecule (negative differential resistance). This allows for keeping the electron flow through the device at a specific level and for controlling the current through the device by the redox state of the tetrapyrrole ring. In the orthogonal orientation, neither of the porphyrin side groups directly participates in the electron transfer through the heme and can thus be used for porphyrin binding and orientation to proteins or electrodes. These results open the possibility for the construction of a highly integrated electronic field effect transistor in a single molecule with controllable electron transfer through individual iron atoms.
    Keywords: ATK; Application; molecular electronics; nanotube; negative differential resistance; histidine; heme; porphyrin;
    Area: molecular electronics
    BibTeX:
    @article{Lebedev2013,
      author = {Lebedev, Nikolai and Griva, Igor and Blom, Anders},
      title = {Internal Control of Electron Transfer through a Single Iron Atom by Chelating Porphyrin},
      booktitle = {The Journal of Physical Chemistry C},
      journal = {J. Phys. Chem. C},
      publisher = {American Chemical Society},
      year = {2013},
      volume = {117},
      number = {14},
      pages = {6933--6939},
      doi = {http://dx.doi.org/10.1021/jp311686c}
    }
    
    Lili Lin, Jun Jiang & Yi Luo Elastic and inelastic electron transport in metal-molecule(s)-metal junctions 2013 Physica E: Low-dimensional Systems and Nanostructures
    Vol. 47(0), 167-187 
    DOI URL 
    Abstract: An overview of studies on elastic and inelastic electron transport properties of molecular junction devices is presented. The development of the experimental fabrication and characterization of molecular junctions as well as the corresponding theoretical modeling is briefly summarized. The functions of molecular devices are generally governed by the intrinsic structure-property relationships, and strongly affected by various environment factors including temperature, solvent and intermolecular interactions. Those detailed structural and environmental information could be probed by a powerful tool of inelastic electron tunneling spectroscopy, for which the theoretical modeling becomes particularly important. With many successful examples, it is demonstrated that the combination of theoretical simulations and experimental measurements can help not only to understand the electron-phonon interaction, but more importantly also to accurately determine the real configurations of molecules inside the junctions.
    Keywords: ATK; Application; Review; molecular electronics; single-molecule conductance; self-assembled monolayers; current-voltage characteristics; carbon nanotube electrodes; tunneling spectroscopy; charge-transport; room-temperature; distance-dependence; quantum transport; organic-molecules
    Area: molecular electronics
    BibTeX:
    @article{Lin2013,
      author = {Lin, Lili and Jiang, Jun and Luo, Yi},
      title = {Elastic and inelastic electron transport in metal-molecule(s)-metal junctions},
      journal = {Physica E: Low-dimensional Systems and Nanostructures},
      year = {2013},
      volume = {47},
      number = {0},
      pages = {167--187},
      url = {http://www.sciencedirect.com/science/article/pii/S1386947712004213},
      doi = {http://dx.doi.org/10.1016/j.physe.2012.10.017}
    }
    
    Y.L. Liu, X.Q. Deng & X.C. Duan The electronic transport properties for a single-wall ZnO nanotube with different coupling interfaces 2013 Physica E: Low-dimensional Systems and Nanostructures
    Vol. 52(0), 21-26 
    DOI URL 
    Abstract: The transport properties of a single-wall ZnO nanotube contacted with two Au (Al or Cu ) electrodes are investigated by a theoretical approach. Our results suggest the contact resistance for ZnO nanotube connected with Au electrodes is the largest one as compared with Al and Cu acting as electrodes. The local density of states (LDOS) near the ZnO nanotube/Cu(Al) interface shows the strong electronic interaction. Also shown is that for Au-ZnO system, we can observe a best rectifying performance, the next is the Al-ZnO system, and the third is Cu-ZnO system. This rectification is also fully rationalized by the calculated transmission spectra, the spatial distribution of the lowest unoccupied molecular orbital and highest occupied molecular orbital states, and the electrostatic potential distribution.
    Keywords: ATK; Application; ZnO nanotube; rectification; coupling interface; density functional theory; contact resistance
    Area: nanotubes
    BibTeX:
    @article{Liu2013a,
      author = {Liu, Y.L. and Deng, X.Q. and Duan, X.C.},
      title = {The electronic transport properties for a single-wall ZnO nanotube with different coupling interfaces},
      journal = {Physica E: Low-dimensional Systems and Nanostructures},
      year = {2013},
      volume = {52},
      number = {0},
      pages = {21--26},
      url = {http://www.sciencedirect.com/science/article/pii/S1386947713000817},
      doi = {http://dx.doi.org/10.1016/j.physe.2013.03.016}
    }
    
    Nadine Seidel, Torsten Hahn, Simon Liebing, Wilhelm Seichter, Jens Kortus & Edwin Weber Synthesis and properties of new 9,10-anthraquinone derived compounds for molecular electronics 2013 New J. Chem.
    Vol. 37(3), 601-610 
    DOI  
    Abstract: Fourteen new derivatives of 9,10-anthraquinone or 9,10-dimethoxyanthracene were designed, synthesised and characterised. Regarding the structure, the compounds are [small pi]-conjugated (cross and linear, respectively) and feature thiophene terminated side arms attached to five different positions of the anthraquinone or anthracene core. The synthesis of the compounds involves a cross-coupling procedure in the key reaction steps. Crystal structures of compounds 5 and 19 have been studied. The thiophene containing title compounds 1-5 can be reduced and oxidised by a two step redox process. The electrochemical parameters have been analysed by cyclic voltammetry (CV). Theoretical calculations in the framework of all-electron density functional theory (DFT) were used to investigate the electronic structure of the individual free molecules. Furthermore, calculations of the transport properties of model devices containing compounds 1-3 and respective reduced hydroquinone derivatives assembled at Au(111) electrodes were carried out to evaluate their potential for the application as redox-active switches.
    Keywords: ATK; Application; molecular electronics; alligator clips; electrochemical properties; anion-radicals; anthraquinone; derivatives; dimethylformamide; approximation; intensities; components; efficient
    Area: molecular electronics
    BibTeX:
    @article{Seidel2013,
      author = {Seidel, Nadine and Hahn, Torsten and Liebing, Simon and Seichter, Wilhelm and Kortus, Jens and Weber, Edwin},
      title = {Synthesis and properties of new 9,10-anthraquinone derived compounds for molecular electronics},
      journal = {New J. Chem.},
      publisher = {The Royal Society of Chemistry},
      year = {2013},
      volume = {37},
      number = {3},
      pages = {601--610},
      doi = {http://dx.doi.org/10.1039/C2NJ40772H}
    }
    
    Colin Van Dyck, Victor Geskin, Auke J. Kronemeijer, Dago M. de Leeuw & Jerome Cornil Impact of derivatization on electron transmission through dithienylethene-based photoswitches in molecular junctions 2013 Phys. Chem. Chem. Phys.
    Vol. 15(12), 4392-4404 
    DOI  
    Abstract: We report a combined Non-Equilibrium Green's Function - Density Functional Theory study of molecular junctions made of photochromic diarylethenes between gold electrodes. The impact of derivatization of the molecule on the transmission spectrum is assessed by introducing: (i) substituents on the diarylethene core; and (ii) linker substituents between the gold surface and the diarylethene. We illustrate that substituents on the core shift considerably the HOMO/LUMO level energies in gas phase but do not change the I-V characteristics of the molecular junctions; this behaviour has been rationalized by establishing links between the transmission spectrum and interfacial electronic reorganization upon chemisorption. In contrast, the different linker substituents under study modulate the conductivity of the junction by changing the degree of orbital hybridization with the metallic electrodes and the degree of orbital polarization.
    Keywords: ATK; Application; molecular electronics; generalized gradient approximation; quantum transport; single-molecule; optical-properties; gold electrodes; devices; conductance; diarylethenes; density; isomerization
    Area: molecular electronics
    BibTeX:
    @article{VanDyck2013,
      author = {Van Dyck, Colin and Geskin, Victor and Kronemeijer, Auke J. and de Leeuw, Dago M. and Cornil, Jerome},
      title = {Impact of derivatization on electron transmission through dithienylethene-based photoswitches in molecular junctions},
      journal = {Phys. Chem. Chem. Phys.},
      publisher = {The Royal Society of Chemistry},
      year = {2013},
      volume = {15},
      number = {12},
      pages = {4392--4404},
      doi = {http://dx.doi.org/10.1039/C3CP44132F}
    }
    
    YaQin Wang, YueE. Xie, ZaiLan Zhang, Ye Zhang & YuanPing Chen Spin-polarized transport in zigzag graphene nanoribbons adsorbing nonmagnetic atomic chain 2013 European Physical Journal B
    Vol. 86(2)The European Physical Journal B, 1-6 
    DOI  
    Abstract: The spin-polarized transport properties of nonmagnetic (metallic Al and nonmetallic C) atomic chains adsorbed on zigzag graphene nanoribbons (ZGNRs) are investigated by the density functional theory (DFT) combined with the nonequilibrium Green's function method. We find that the spin polarization of ZGNRs is sensitive to the adsorption sites and atomic types of the chains. As an Al chain is adsorbed on the middle of ZGNR, no spin-polarized transport arises. As the Al chain is adsorbed on the edge of ZGNR, high spin polarization is produced around the Fermi level. The different transport behaviors are originated from the fact that the edge adsorption of Al chain breaks the magnetization symmetry of two edges while the middle adsorption of Al chain only modifies the magnetizations of two edges equally. More prominent spin polarization is generated as a C chain is adsorbed on the edge of ZGNR. The complete spin polarization emerges not only around the Fermi level but also far from the Fermi level, owing to the edge states and the localized states. These results indicate that one can effectively modulate the spin-polarized transports of ZGNRs through adsorbing different nonmagnetic atomic chains.
    Keywords: ATK; Application; graphene nanoribbon; spin; adsorbed atoms; doping; spin-polarized transport
    Area: graphene; spin
    BibTeX:
    @article{Wang2013a,
      author = {Wang, YaQin and Xie, YueE. and Zhang, ZaiLan and Zhang, Ye and Chen, YuanPing},
      title = {Spin-polarized transport in zigzag graphene nanoribbons adsorbing nonmagnetic atomic chain},
      booktitle = {The European Physical Journal B},
      journal = {European Physical Journal B},
      publisher = {Springer-Verlag},
      year = {2013},
      volume = {86},
      number = {2},
      pages = {1-6},
      doi = {http://dx.doi.org/10.1140/epjb/e2012-30912-5}
    }
    
    Huaping Xiao, Chuanxiao Zhang, Kaiwang Zhang, Lizhong Sun & Jianxin Zhong Tunable differential conductance of single wall C/BN nanotube heterostructure 2013 Journal of Molecular Modeling
    Vol. 2013Journal of Molecular Modeling, 1-5 
    DOI  
    Abstract: The transport properties and differential conductance of the heterostructures constructed by (5,5) single wall carbon nanotube (SWCNT) and (5,5) single wall boron nitride nanotube (SWBNNT) are investigated using density functional theory in combination with non-equilibrium Green's functions. We find that the transmission conductance of (5,5) BN/C nanotube heterostructure is not only continually depressed as the BNNT region increases but also the drop of the conductance is uniform in the energy window (-1.43 eV, 1 eV), which leads to linear I-V dependence for the systems when the bias is within this energy range. Moreover, the differential conductance linearly decreases when n<=3 but exponentially decreases when n>=3 for (5,5)(BN) n /C heterostructure. Such tunable differential conductance of (5,5) BN/C nanotube heterostructure mainly derives from the blockage of the transport channels induced by the semiconductive BN segment.
    Keywords: ATK; Application; boron-nitride; C/BN nanotube heterostructure; differential conductance; transport property
    Area: nanotubes
    BibTeX:
    @article{Xiao2013a,
      author = {Xiao, Huaping and Zhang, Chuanxiao and Zhang, Kaiwang and Sun, Lizhong and Zhong, Jianxin},
      title = {Tunable differential conductance of single wall C/BN nanotube heterostructure},
      booktitle = {Journal of Molecular Modeling},
      journal = {Journal of Molecular Modeling},
      publisher = {Springer-Verlag},
      year = {2013},
      volume = {2013},
      pages = {1-5},
      doi = {http://dx.doi.org/10.1007/s00894-013-1823-y}
    }
    
    Chengyu Yang & Quanfang Chen Electronic structure and transport properties of carbon nanotube adsorbed with a copper chain 2013 International Journal of Smart and Nano Materials
    Vol. 2013International Journal of Smart and Nano Materials, 1-7 
    DOI  
    Abstract: The authors have studied the electronic structure and transport properties of hybrid nanowires made of a copper chain adsorbed on a single-wall carbon nanotube (CNT) using first principle methods. Results have shown that after the adsorption of the Cu chain, the density of states and the transmission coefficients of the CNT (5, 5)/Cu nanowire have been increased, while the band gap of CNT (10, 0)/Cu have been significantly reduced. These results imply that the conductivity of CNTs, either metallic or semiconducting, have been enhanced by the adsorption of a copper chain. These hybrid nanowires with enhanced conductivity may be suitable for nanoelectronics.
    Keywords: ATK; Application; nanotubes; atomic chain; nanowire
    Area: nanotubes
    BibTeX:
    @article{Yang2013,
      author = {Yang, Chengyu and Chen, Quanfang},
      title = {Electronic structure and transport properties of carbon nanotube adsorbed with a copper chain},
      booktitle = {International Journal of Smart and Nano Materials},
      journal = {International Journal of Smart and Nano Materials},
      publisher = {Taylor & Francis},
      year = {2013},
      volume = {2013},
      pages = {1--7},
      doi = {http://dx.doi.org/10.1080/19475411.2013.782906}
    }
    
    P. Zhao & D.S. Liu Negative differential resistance behavior in molecular devices based on carbon nanotubes: Effects of chirality and electrode–electrode distance 2013 Physica E: Low-dimensional Systems and Nanostructures
    Vol. 47(0), 224-228 
    DOI URL 
    Abstract: Using first-principles density functional theory and real-space non-equilibrium Green′s function formalism for quantum transport calculation, we investigate all-carbon mechanically controlled molecular devices which consists of only two (5,5) armchair and two (6,0) zigzag single-walled carbon nanotubes (SWCNTs) opposing one another. Our results show that the chirality of SWCNTs and the electrode–electrode distance have crucial effects on the electronic transport properties of such systems. When the right SWCNT electrode is mechanically pushed forward along its axial direction, obvious negative differential resistance behaviors are observed in the zigzag system, but not in the armchair case.
    Keywords: ATK; Application; molecular electronics; transport-properties; field-emission; wire; conductance; junction; graphene; state
    Area: molecular electronics
    BibTeX:
    @article{Zhao2013e,
      author = {Zhao, P. and Liu, D.S.},
      title = {Negative differential resistance behavior in molecular devices based on carbon nanotubes: Effects of chirality and electrode–electrode distance},
      journal = {Physica E: Low-dimensional Systems and Nanostructures},
      year = {2013},
      volume = {47},
      number = {0},
      pages = {224--228},
      url = {http://www.sciencedirect.com/science/article/pii/S1386947712004493},
      doi = {http://dx.doi.org/10.1016/j.physe.2012.11.008}
    }
    
    Vladimir Kolchuzhin, Jan Mehner, Milind Shende, Erik Markert, Ulrich Heinkel, Christian Wagner & Thomas Gessner System Level Modelling of CNT based Mechanical Sensor 2013 Chemnitzer Fachtagung Mikrosystemtechnik
    Vol. 11, 1-6 
    URL 
    Abstract: This article presents a system level model of carbon nanotube (CNT) based mechanical sensor, which consists of micro-electro-mechanical (MEMS) platform that is served to actuate single-axis force and single CNT is placed between the movable and fixed electrodes. The change in conductivity of CNT, when strain is applied, is used to measure force or displacement. The simulation of the whole sensor element will be achieved by using the framework of hardware description languages (VHDL-AMS and SystemC-AMS) that uses compact models to describe sub-elements performing heterogeneous functions. The CNT piezoresistive compact model presented in the article is based on the analytical model and the simulations results from density functional theory (DFT). The macromodel of the MEMS platform is build using mode superposition technique. The results of the system simulations are presented and discussed in the article.
    Keywords: ATK; Application; nanotube; piezoelectric effect; mechanical sensor; compact model; DFT;
    Area: nanotubes
    BibTeX:
    @article{Kolchuzhin2013,
      author = {Kolchuzhin, Vladimir and Mehner, Jan and Shende, Milind and Markert, Erik and Heinkel, Ulrich and Wagner, Christian and Gessner, Thomas},
      title = {System Level Modelling of CNT based Mechanical Sensor},
      journal = {Chemnitzer Fachtagung Mikrosystemtechnik},
      year = {2013},
      volume = {11},
      pages = {1-6},
      url = {http://www.researchgate.net/publication/235338375_System_Level_Modelling_of_CNT_based_Mechanical_Sensor/file/32bfe5110c3b56b43e.pdf}
    }
    
    Yukihito Matsuura & Toshifumi Morioka Quantum Transport in mu-Cyclopentadienyl Indium Complex 2013 Molecular Crystals and Liquid Crystals
    Vol. 574(1)Molecular Crystals and Liquid Crystals, 135-142 
    DOI  
    Abstract: The electronic structure and conductance of a mu-cyclopentadienyl indium (Cp-In) multidecker complex have been examined by using the density functional theory (DFT). The electrical conduction of the complex between gold electrodes is investigated by using Green's function formalism. The one-dimensional band structure exhibited semiconducting properties. The Cp5In4- complex, which had a long molecular length, between gold electrodes, exhibited low electrical conduction. On the other hand, the Cp3In2- complex between the gold electrodes had transmission at the Fermi level. The I-V curves suggest the intrinsic characteristics of semiconducting properties and the suppression of strong tunneling effect.
    Keywords: ATK; Application; molecular electronics
    Area: molecular electronics
    BibTeX:
    @article{Matsuura2013a,
      author = {Matsuura, Yukihito and Morioka, Toshifumi},
      title = {Quantum Transport in mu-Cyclopentadienyl Indium Complex},
      booktitle = {Molecular Crystals and Liquid Crystals},
      journal = {Molecular Crystals and Liquid Crystals},
      publisher = {Taylor & Francis},
      year = {2013},
      volume = {574},
      number = {1},
      pages = {135--142},
      doi = {http://dx.doi.org/10.1080/15421406.2012.763016}
    }
    
    Xiaozan Wu, Guanghui Huang, Qingbin Tao & Hui Xu Effect of boron/nitrogen codoping on transport properties of C60 molecular devices 2013 J. Cent. South Univ.
    Vol. 20, 889-893 
    DOI  
    Abstract: By using nonequilibrium Green's function method and firstprinciples calculations, the electronic transport properties of doped C60 molecular devices were investigated. It is revealed that the C60 molecular devices show the metal behavior due to the interaction between the C60 molecule and the metal electrode. The current-voltage curve displays a linear behavior at low bias, and the currents have the relation of M1>M3>M4>M2 when the bias voltage is lower than 0.6 V. Electronic transport properties are affected greatly by the doped atoms. Negative differential resistance is found in a certain bias range for C60 and C58BN molecular devices, but cannot be observed in C59B and C59N molecular devices. These unconventional effects can be used to design novel nanoelectronic devices.
    Keywords: ATK; Application; negative differential resistance; molecular device; electronic transport property; first-principles calculation
    Area: molecular electronics
    BibTeX:
    @article{Wu2013a,
      author = {Wu, Xiaozan and Huang, Guanghui and Tao, Qingbin and Xu, Hui},
      title = {Effect of boron/nitrogen codoping on transport properties of C60 molecular devices},
      journal = {J. Cent. South Univ.},
      year = {2013},
      volume = {20},
      pages = {889-893},
      doi = {http://dx.doi.org/10.1007/s11771-013-1562-3}
    }
    
    P. Zhao, D.S. Liu, S.J. Li & G. Chen Modulation of rectification and negative differential resistance in graphene nanoribbon by nitrogen doping 2013 Physics Letters A
    Vol. 377(15), 1134-1138 
    DOI  
    Abstract: Abstract By applying the nonequilibrium Green's function formalism combined with density functional theory, we have investigated the electronic transport properties of two nitrogen-doped armchair graphene nanoribbon-based junctions M1 and M2. In the left part of M1 and M2, nitrogen atoms are doped at two edges of the nanoribbon. In the right part, nitrogen atoms are doped at one edge and at the center for M1 and M2, respectively. Obvious rectifying and negative differential resistance behaviors are found, which are strongly dependent on the doping position. The maximum rectification and peak-to-valley ratios are up to the order of 10^4 in M2.
    Keywords: ATK; Application; graphene nanoribbon; electronic transport; rectification; negative differential resistance; NDR;
    Area: graphene
    BibTeX:
    @article{Zhao2013b,
      author = {Zhao, P. and Liu, D.S. and Li, S.J. and Chen, G.},
      title = {Modulation of rectification and negative differential resistance in graphene nanoribbon by nitrogen doping},
      journal = {Physics Letters A},
      year = {2013},
      volume = {377},
      number = {15},
      pages = {1134--1138},
      doi = {http://dx.doi.org/10.1016/j.physleta.2013.02.048}
    }
    
    JingFen Zhao, ChuanLu Yang, MeiShan Wang & Jie Ma First-principles analysis of the effect of contact sites on electronic transport properties of diaminofluorene 2013 Physica B: Condensed Matter
    Vol. 417(0), 70-74 
    DOI  
    Abstract: The effects of atop, hollow, bridge and adatom contact sites on the electronic transport properties of a single diaminofluorene molecule connected to gold electrodes are studied by using nonequilibrium Green's functions in combination with the density functional theory. Computational results were analyzed to identify the contact site utilized in the experiment of Lu et al. (2009) [26]. Current-voltage curves were also examined. The rectifying behavior of diaminofluorene was observed in the atop, hollow and bridge contact sites. The highest occupied molecular orbital, the lowest unoccupied molecular orbital and transmission spectra were used in determining the various electronic transport properties of diaminofluorene.
    Keywords: ATK; Application; rectifying behavior; contact sites; nonequilibrium Green's function; density functional theory; electronic transport; molecular electronics
    Area: molecular electronics
    BibTeX:
    @article{Zhao2013c,
      author = {Zhao, JingFen and Yang, ChuanLu and Wang, MeiShan and Ma, Jie},
      title = {First-principles analysis of the effect of contact sites on electronic transport properties of diaminofluorene},
      journal = {Physica B: Condensed Matter},
      year = {2013},
      volume = {417},
      number = {0},
      pages = {70--74},
      doi = {http://dx.doi.org/10.1016/j.physb.2013.02.007}
    }
    
    P. Zhao, D.S. Liu & G. Chen Effect of mono-vacancy on transport properties of zigzag carbon- and boron-nitride-nanotube heterostructures 2013 Solid State Communications
    Vol. 160(0), 13-16 
    DOI  
    Abstract: On the basis of first-principles density functional theory and non-equilibrium Green's function technique, we have investigated the effects of a mono-vacancy on the electronic transport properties of the carbon nanotube/boron nitride nanotube heterostructures. The results show that the electronic transport properties are strongly dependent on the position of the mono-vacancy, and the negative differential resistance and rectifying performances can be strengthened or weakened alternately with the position change of the mono-vacancy. Moreover, the performance change is more significant when the mono-vacancy occurs on the carbon nanotube part. These interesting phenomena are explained in terms of the evolution of the transmission spectrum with applied bias combined with molecular projected self-consistent Hamiltonian states analysis.
    Keywords: ATK; Application; boron-nitride; nanotube; vacancy electronic transport; negative differential resistance; rectifying; molecular electronics
    Area: nanotubes
    BibTeX:
    @article{Zhao2013d,
      author = {Zhao, P. and Liu, D.S. and Chen, G.},
      title = {Effect of mono-vacancy on transport properties of zigzag carbon- and boron-nitride-nanotube heterostructures},
      journal = {Solid State Communications},
      year = {2013},
      volume = {160},
      number = {0},
      pages = {13--16},
      doi = {http://dx.doi.org/10.1016/j.ssc.2013.02.007}
    }
    
    Bagavathi Chandrasekara Nanotransistors from metal and metalloid compound nanotubes 2013 International Journal of Scientific & Engineering Research
    Vol. 4(2), 1-4 
    URL 
    Abstract: The escalating trend of chip integration and miniaturization has dared the designers to seek to a nascent phenomenon to save the Moore's law. Due to continuous reduction in device size, the so-far-unseen quantum effects have dominated the device physics. The solution to this crisis is nanoelectronics. Nano structures are used to develop new devices by utilizing the quantum effects. III group compounds have been known for their special properties as semiconductors in electronics. By including nanoscale nature with III group compounds, greater advantages can be obtained. III group nitride nanotubes have been investigated in many works. The nanotubes under discussion are boron nitride nanotubes and gallium nitride nanotubes. The phenomenon used for analysis in this work is Density Functional Theory (DFT). The characteristics of a device can be deduced from the electronic cloud structure around the device through density functional theory. In this work, III group nitride nanotubes are employed as transistor channels and their characteristics are scrutinized through simulation studies.
    Keywords: ATK; Application; transistor; boron-nitride; nanotube; gallium nitride; nanotube transistor; third group nanotubes; density functional theory; simulation of nanomaterials
    Area: nanotubes
    BibTeX:
    @article{Chandrasekara2013,
      author = {Bagavathi Chandrasekara},
      title = {Nanotransistors from metal and metalloid compound nanotubes},
      journal = {International Journal of Scientific & Engineering Research},
      year = {2013},
      volume = {4},
      number = {2},
      pages = {1-4},
      url = {http://www.ijser.org/researchpaper/NANOTRANSISTORS-FROM-METAL-AND-METALLOID-COMPOUND-NANOTUBES.pdf}
    }
    
    Pengwei Li, Zhi Yang, Wendong Zhang & Shijie Xiong The magnetic properties and spin-filter effects of manganese-borazine sandwich clusters 2013 Journal of Molecular Structure
    Vol. 1038(0), 1-7 
    DOI URL 
    Abstract: In present paper, detailed investigations on the magnetic and quantum transport properties of Mn_n(B_3N_3H_6)_n+1 (n = 1-4) sandwich clusters were performed by using density functional theory and non-equilibrium Green's function technique. The calculated results show that these clusters are stable and adopt ferromagnetic orders as the ground states. When coupled to Ni electrodes, the sandwiches could exhibit novel quantum transport properties such as high spin-filter capabilities and negative differential resistance effects, indicating that these sandwich systems could be viewed as a new kind of spin filter.
    Keywords: ATK; Application; molecular electronics; sandwich; cluster; spin filter
    Area: molecular electronics; spin
    BibTeX:
    @article{Li2013a,
      author = {Li, Pengwei and Yang, Zhi and Zhang, Wendong and Xiong, Shijie},
      title = {The magnetic properties and spin-filter effects of manganese-borazine sandwich clusters},
      journal = {Journal of Molecular Structure},
      year = {2013},
      volume = {1038},
      number = {0},
      pages = {1--7},
      url = {http://www.sciencedirect.com/science/article/pii/S0022286013000331},
      doi = {http://dx.doi.org/10.1016/j.molstruc.2013.01.022}
    }
    
    Qing-Qing Sun, Yong-Jun Li, Jin-Lan He, Wen Yang, Peng Zhou, Hong-Liang Lu, Shi-Jing Ding & David Wei Zhang The physics and backward diode behavior of heavily doped single layer MoS2 based p-n junctions 2013 Applied Physics Letters
    Vol. 102(9), 093104 
    DOI  
    Abstract: The single layer MoS2 is attractive for the use in the next-generation low power nanoelectronic devices because of its intrinsic bandgap compared to graphene. In this work, we investigated the transport property of a p-n junction based on two-dimensional MoS2. The n-type and p-type doping are realized through substituting sulfur with chlorine and phosphorus. The device exhibited backward diode-like behavior with large rectifying ratios. We attribute the observed current-voltage characteristics to different heavy doping effect caused by chlorine and phosphorus. Our results may throw light on the electronic modulation of MoS2 and realizations of complemented logics devices based on MoS2.
    Keywords: ATK; Application; MoS2; p-n junction; diodes; energy gap; molybdenum compounds; rectification; transistors; graphene
    Area: graphene; dichalcogenides
    BibTeX:
    @article{Sun2013,
      author = {Sun, Qing-Qing and Li, Yong-Jun and He, Jin-Lan and Yang, Wen and Zhou, Peng and Lu, Hong-Liang and Ding, Shi-Jing and Zhang, David Wei},
      title = {The physics and backward diode behavior of heavily doped single layer MoS2 based p-n junctions},
      journal = {Applied Physics Letters},
      publisher = {AIP},
      year = {2013},
      volume = {102},
      number = {9},
      pages = {093104},
      doi = {http://dx.doi.org/10.1063/1.4794802}
    }
    
    Fang Wang, Yonglai Zhang, Yang Liu, Xuefeng Wang, Mingrong Shen, Shuit-Tong Lee & Zhenhui Kang Opto-electronic conversion logic behaviour through dynamic modulation of electron/energy transfer states at the TiO2-carbon quantum dot interface 2013 Nanoscale
    Vol. 5(5), 1831-1835 
    DOI  
    Abstract: Here we show a bias-mediated electron/energy transfer process at the CQDs-TiO2 interface for the dynamic modulation of opto-electronic properties. Different energy and electron transfer states have been observed in the CQDs-TNTs system due to the up-conversion photoluminescence and the electron donation/acceptance properties of the CQDs decorated on TNTs.
    Keywords: ATK; Application; TiO2 nanotube; phonons; photoluminescence; optoelectronics; doping; visible-light; carbon; photocatalyst; nanotubes; circuits
    Area: nanotubes
    BibTeX:
    @article{Wang2013,
      author = {Wang, Fang and Zhang, Yonglai and Liu, Yang and Wang, Xuefeng and Shen, Mingrong and Lee, Shuit-Tong and Kang, Zhenhui},
      title = {Opto-electronic conversion logic behaviour through dynamic modulation of electron/energy transfer states at the TiO2-carbon quantum dot interface},
      journal = {Nanoscale},
      publisher = {The Royal Society of Chemistry},
      year = {2013},
      volume = {5},
      number = {5},
      pages = {1831--1835},
      doi = {http://dx.doi.org/10.1039/C3NR33985H}
    }
    
    H.P. Xiao, Chaoyu He, C.X. Zhang, L.Z. Sun, Pan Zhou & Jianxin Zhong Stability, electronic structures and transport properties of armchair (10, 10) BN/C nanotubes 2013 Journal of Solid State Chemistry
    Vol. 200(0), 294-298 
    DOI URL 
    Abstract: Using the first-principle calculations, the stability and electronic properties of two novel types of four-segment armchair (10, 10) BN/C hybrid nanotubes ((BN)5C5(BN)5C5NT and (BN)5C5(NB)5C5NT) as well as two-segment armchair (10, 10) BN/C hybrid nanotubes ( ( BN 20-n C n NTs ) are systematically investigated. When n increases from 1 to 4, the band gap of ( BN ) 20-n C n NTs gradually decreases to a narrow one. When 4<=n<=17 , the electronic structure of carbon segment in ( BN ) 20-n C n NTs behaves as zigzag graphene nanoribbons whose band gap is modulated by an inherent electric field of the BN segment. ZGNR-like segments in (BN)5C5(BN)5C5NT and (BN)5C5(NB)5C5NT behave as narrow gap semiconductor and metal, respectively, due to their different chemical environment. Moreover, the (BN)5C5(NB)5C5NT can separate electron and hole carriers, indicating its potential application in solar cell materials. Obvious transport enhancement around the Fermi level is found in the four-segment nanotubes, especially a 6G0 transmission peak in the metallic (BN)5C5(NB)5C5NT.
    Keywords: ATK; Application; boron-nitride carbon hybrid nanotubes; density functional theory; non-equilibrium Green's function; electronic properties; transport properties
    Area: nanotubes
    BibTeX:
    @article{Xiao2013,
      author = {Xiao, H.P. and He, Chaoyu and Zhang, C.X. and Sun, L.Z. and Zhou, Pan and Zhong, Jianxin},
      title = {Stability, electronic structures and transport properties of armchair (10, 10) BN/C nanotubes},
      journal = {Journal of Solid State Chemistry},
      year = {2013},
      volume = {200},
      number = {0},
      pages = {294--298},
      url = {http://www.sciencedirect.com/science/article/pii/S002245961300042X},
      doi = {http://dx.doi.org/10.1016/j.jssc.2013.01.026}
    }
    
    Peng Zhao, De-Sheng Liu, Hai-Ying Liu, Shu-Juan Li & Gang Chen Low bias negative differential resistance in C60 dimer modulated by gate voltage 2013 Organic Electronics
    Vol. 14(4), 1109-1115 
    DOI URL 
    Abstract: By using a combined method of density functional theory and nonequilibrium Green's function formalism, we investigate the electronic transport properties of a gated C60 dimer molecule sandwiched between two gold electrodes. The results show that the gate voltage can strongly affect the electronic transport properties of the C60 dimer and change it from semiconducting to metallic. Negative differential resistance behaviors are obtained in such systems and can be modulated to occur at much lower bias by the gate voltage. The low bias negative differential resistance is analyzed from the calculated transmission spectra, projected density of states and the spatial distribution of molecular projected self-consistent Hamiltonian orbitals along with the voltage drop. These results provide a theoretical support to the design of low bias negative differential resistance molecular device by using the modulation of gate voltage.
    Keywords: ATK; Application; fullerene; electronic transport; negative differential resistance; NDR;
    Area: molecular electronics; fullerenes
    BibTeX:
    @article{Zhao2013a,
      author = {Zhao, Peng and Liu, De-Sheng and Liu, Hai-Ying and Li, Shu-Juan and Chen, Gang},
      title = {Low bias negative differential resistance in C60 dimer modulated by gate voltage},
      journal = {Organic Electronics},
      year = {2013},
      volume = {14},
      number = {4},
      pages = {1109--1115},
      url = {http://www.sciencedirect.com/science/article/pii/S1566119913000529},
      doi = {http://dx.doi.org/10.1016/j.orgel.2013.01.034}
    }
    
    Jiaping Fan, Nahashon Ndegwa Gathitu, Yingfei Chang & Jingping Zhang Effect of length on the position of negative differential resistance and realization of multifunction in fused oligothiophenes based molecular device 2013 The Journal of Chemical Physics
    Vol. 138(7), 074307 
    DOI  
    Abstract: The length modulation of electron transport properties for molecular devices based on fused oligothiophenes has been investigated theoretically using a combination of non-equilibrium Green's functions and first-principles density functional theory. The results show that the lengths of the molecules have a distinct influence on the position of negative differential resistance (NDR) of the molecular devices. By exploring the effect on transmission properties of substituent groups, hexathieno[3,2-b:2',3'-d]thiophene with -NH2 and -NO2 substituents (model L) can be regard as a good candidate of multifunctional molecular device, which shows excellent rectifying performance (the largest rectification ration is 14.3 at 1.2 V) and clear NDR behavior (at 1.4 V).
    Keywords: ATK; Application; electric properties; Green's function methods; molecular electronics; nanoelectronics; nitrogen compounds; organic compounds; ab-initio; 1st-principles; conductance; contact; transport; junction
    Area: molecular electronics
    BibTeX:
    @article{Fan2013,
      author = {Fan, Jiaping and Gathitu, Nahashon Ndegwa and Chang, Yingfei and Zhang, Jingping},
      title = {Effect of length on the position of negative differential resistance and realization of multifunction in fused oligothiophenes based molecular device},
      journal = {The Journal of Chemical Physics},
      publisher = {AIP},
      year = {2013},
      volume = {138},
      number = {7},
      pages = {074307},
      doi = {http://dx.doi.org/10.1063/1.4790805}
    }
    
    Zhi-Qiang Fan, Zhen-Hua Zhang, Xiao-Qing Deng, Gui-Ping Tang & Ke-Qiu Chen Controllable low-bias negative differential resistance and rectifying behaviors induced by symmetry breaking 2013 Applied Physics Letters
    Vol. 102(2), 023508 
    DOI  
    Abstract: Incorporating the characteristic of pyramidal electrode and symmetry breaking of molecular structure, we theoretically design a molecular device to perform negative differential resistance and rectifying behaviors simultaneously. The calculated results reveal that low-bias negative differential resistance behaviors can appear symmetrically when tetraphenyl molecule connects to pyramidal gold electrodes. However, as one phenyl of tetraphenyl molecule is replaced by a pyrimidyl, the symmetry breaking on the molecule will break the symmetry of negative differential resistance behavior. The peak-to-valley ratio on negative bias region is larger than that on positive bias region to perform a low-bias rectifying behavior. More importantly, increasing the symmetry breaking can further weaken these two behaviors which propose an effective way to modulate them.
    Keywords: ATK; Application; gold; metal-insulator boundaries; molecular electronics; negative resistance; organic compounds; rectification; molecular rectifiers; atomic-scale device; junction; diode
    Area: molecular electronics
    BibTeX:
    @article{Fan2013a,
      author = {Fan, Zhi-Qiang and Zhang, Zhen-Hua and Deng, Xiao-Qing and Tang, Gui-Ping and Chen, Ke-Qiu},
      title = {Controllable low-bias negative differential resistance and rectifying behaviors induced by symmetry breaking},
      journal = {Applied Physics Letters},
      publisher = {AIP},
      year = {2013},
      volume = {102},
      number = {2},
      pages = {023508},
      doi = {http://dx.doi.org/10.1063/1.4788691}
    }
    
    Afif Gouissem, Wu Fan, Adri C.T. van Duin & Pradeep Sharma A reactive force-field for Zirconium and Hafnium Di-Boride 2013 Computational Materials Science
    Vol. 70(0), 171-177 
    DOI  
    Abstract: Zirconium and Hafnium Di-Boride are the two major material systems that are of critical importance for applications in ultra-high temperature environments where both oxidation and mechanical damage mechanisms (such as creep) are operative. Atomistic simulations of these materials at finite temperatures have been hampered due to the unavailability of inter-atomic potentials for the involved elements. In this paper, we present the development of interatomic potentials for both ZrB2 and HfB2 within the ReaxFF framework, thus enabling modeling of chemical reactions. The parameters of the reactive force field are derived by fitting to detailed quantum mechanical simulations of ZrB2 and HfB2 clusters and crystal structures.
    Keywords: ATK; Application; interatomic force-field; chemical reactions; high temperature materials; reaxFF; fitting
    Area: semi
    BibTeX:
    @article{Gouissem2013,
      author = {Gouissem, Afif and Fan, Wu and van Duin, Adri C.T. and Sharma, Pradeep},
      title = {A reactive force-field for Zirconium and Hafnium Di-Boride},
      journal = {Computational Materials Science},
      year = {2013},
      volume = {70},
      number = {0},
      pages = {171--177},
      doi = {j.commatsci.2012.12.038}
    }
    
    Jing Huang, Qunxiang Li & Jinlong Yang Tuning the Electronic Properties of N@C60 Molecule: A Theoretical Study 2013 Journal of Nanoscience and Nanotechnology
    Vol. 13(2), 1053-1058 
    DOI  
    Abstract: We used first-principle calculations to explore the electronic and transport properties of N@C60 molecule. The calculated results indicate that the N atom locates at either slight or significant off-center in C60 cage under various different chemical environments. The localized N atomic magnetic moment in N@C60 molecule is about 3.0 muB, which is not sensitive to the chemical environment, such as the carrier doping, the external electric field, and the molecule-substrate interaction. On the other hand, the magnetism of N@C60 can be effectively tuned by carrier doping and the cage chemical modification. The C60 cage with delocalized pi-electrons character demonstrates a significant shielding (about 80%) of the encapsulated N atom from the applied external electric field. We do not observe obvious transmission spin polarization in N@C60 molecular junctions and the transmission spectra of two spin channels are similar near the Fermi level.
    Keywords: ATK; Application; molecular electronics; fullerenes
    Area: molecular electronics; fullerenes
    BibTeX:
    @article{Huang2013,
      author = {Huang, Jing and Li, Qunxiang and Yang, Jinlong},
      title = {Tuning the Electronic Properties of N@C60 Molecule: A Theoretical Study},
      journal = {Journal of Nanoscience and Nanotechnology},
      year = {2013},
      volume = {13},
      number = {2},
      pages = {1053--1058},
      doi = {http://dx.doi.org/10.1166/jnn.2013.6116}
    }
    
    Anurag Srivastava, B. Santhibhushan & Pankaj Dobwal Performance analysis of impurity added benzene based single-electron transistor 2013 Appl. Nanosci.
    Vol. 2Applied Nanoscience, 1-7 
    DOI  
    Abstract: We have analyzed the impurity added benzene based single-electron transistor (SET) using the ab initio approach, based on density functional theory and non-equilibrium Green's function. Boron and nitrogen has been added as impurities either by replacing the last carbon atom or last hydrogen in the benzene. The system has been modeled in such a way that the impurity added benzene is placed above the gate dielectric in coulomb blockade regime between source and drain electrodes for weak coupling. The charging energies of the system have been calculated and discussed in both the isolated as well as SET environments. The conductance dependence of SET on bias potential and gate voltage has been verified through charge stability diagrams.
    Keywords: ATK; Application; impurity added benzene (IAB); single-electron transistor (SET); Charge states, Charging energy, Charge stability diagram
    Area: SET
    BibTeX:
    @article{Srivastava2013,
      author = {Srivastava, Anurag and Santhibhushan, B. and Dobwal, Pankaj},
      title = {Performance analysis of impurity added benzene based single-electron transistor},
      booktitle = {Applied Nanoscience},
      journal = {Appl. Nanosci.},
      publisher = {Springer-Verlag},
      year = {2013},
      volume = {2},
      pages = {1-7},
      doi = {http://dx.doi.org/10.1007/s13204-013-0194-0}
    }
    
    F. Tavazza, S. Barzilai, D.T. Smith & L.E. Levine The increase in conductance of a gold single atom chain during elastic elongation 2013 Journal of Applied Physics
    Vol. 113(5), 054316 
    DOI  
    Abstract: The conductance of monoatomic gold wires has been studied using ab initio calculations and the transmission was found to vary with the elastic strain. Counter-intuitively, the conductance was found to increase for the initial stages of the elongation, where the structure has a zigzag shape and the bond angles increase from 140° toward 160°. After a certain elongation limit, where the angles are relatively high, the bond length elongation associated with a Peierls distortion reverses this trend and the conductance decreases. These simulations are in good agreement with previously unexplained experimental results.
    Keywords: ATK; Application; nanowire; conductance quantization; elastic properties; plasticity; ab initio calculations; bond angles; bond lengths; elasticity, electrical conductivity; elongation; gold; geometry optimization; transport; molecules; geometry optimization; transport; molecules
    Area: nanowires
    BibTeX:
    @article{Tavazza2013,
      author = {Tavazza, F. and Barzilai, S. and Smith, D. T. and Levine, L. E.},
      title = {The increase in conductance of a gold single atom chain during elastic elongation},
      journal = {Journal of Applied Physics},
      publisher = {AIP},
      year = {2013},
      volume = {113},
      number = {5},
      pages = {054316},
      doi = {http://dx.doi.org/10.1063/1.4790379}
    }
    
    Jiaxin Zheng, Lu Wang, Ruge Quhe, Qihang Liu, Hong Li, Dapeng Yu, Wai-Ning Mei, Junjie Shi, Zhengxiang Gao & Jing Lu Sub-10 nm Gate Length Graphene Transistors: Operating at Terahertz Frequencies with Current Saturation 2013 Sci. Rep.
    Vol. 3, 1314 
    DOI  
    Abstract: Radio-frequency application of graphene transistors is attracting much recent attention due to the high carrier mobility of graphene. The measured intrinsic cut-off frequency (fT) of graphene transistor generally increases with the reduced gate length (Lgate) till Lgate = 40 nm, and the maximum measured fT has reached 300 GHz. Using ab initio quantum transport simulation, we reveal for the first time that fT of a graphene transistor still increases with the reduced Lgate when Lgate scales down to a few nm and reaches astonishing a few tens of THz. We observe a clear drain current saturation when a band gap is opened in graphene, with the maximum intrinsic voltage gain increased by a factor of 20. Our simulation strongly suggests it is possible to design a graphene transistor with an extraordinary high fT and drain current saturation by continuously shortening Lgate and opening a band gap.
    Keywords: ATK; Application; graphene; scaling laws; applied physics; electronic properties and devices; nanosensors; radio frequency applications; field-effect transistors; walled carbon nanotubes; epitaxial graphene; bilayer graphene; room-temperature; tunable bandgap; boron-nitride; ab-initio; transport; devices
    Area: graphene
    BibTeX:
    @article{Zheng2013a,
      author = {Zheng, Jiaxin and Wang, Lu and Quhe, Ruge and Liu, Qihang and Li, Hong and Yu, Dapeng and Mei, Wai-Ning and Shi, Junjie and Gao, Zhengxiang and Lu, Jing},
      title = {Sub-10 nm Gate Length Graphene Transistors: Operating at Terahertz Frequencies with Current Saturation},
      journal = {Sci. Rep.},
      publisher = {Macmillan Publishers Limited. All rights reserved},
      year = {2013},
      volume = {3},
      pages = {1314},
      doi = {http://dx.doi.org/10.1038/srep01314}
    }
    
    Zhaoqiang Bai, Lei Shen, Qingyun Wu, Minggang Zeng, Jian-Sheng Wang, Guchang Han & Yuan Ping Feng Boron diffusion induced symmetry reduction and scattering in CoFeB/MgO/CoFeB magnetic tunnel junctions 2013 Phys. Rev. B
    Vol. 87(1), 014114- 
    DOI  
    Abstract: By first-principles analysis, we investigate the effect of thermal annealing on structural stability of CoFeB/MgO(thin)/CoFeB magnetic tunnel junctions. The calculated phonon dispersion indicates that Mg3B2O6 (kotoite) is a stable spacer after annealing due to B diffusion into MgO. The calculated tunneling magnetoresistance (TMR) of CoFe/kotoite/CoFe is 210%, which is in good agreement with the available experimental value and 2 orders of magnitude lower than the predicted values of CoFe/MgO/CoFe junctions. The physics of this more realistic TMR value is the change in symmetry from C4v of MgO to C2v of kotoite. Such symmetry reduction induces scattering and weakens the tunneling transmission of the &Delta;1-like Bloch states. Our calculations also reveal that the tunneling transmission is sensitive to the electrode/spacer interfacial chemical bonding. Residual boron, localized at the interface due to insufficient annealing temperature, can further reduce the TMR.
    Keywords: ATK; Application; magnetic tunnel junction; spin; MTJ; diffusion; boron; room-temperature; magnetoresistance; complex bandstructure; transmission eigenstates; transmission pathways;
    Area: interfaces; spin; semi; nvm
    BibTeX:
    @article{Bai2013,
      author = {Bai, Zhaoqiang and Shen, Lei and Wu, Qingyun and Zeng, Minggang and Wang, Jian-Sheng and Han, Guchang and Feng, Yuan Ping},
      title = {Boron diffusion induced symmetry reduction and scattering in CoFeB/MgO/CoFeB magnetic tunnel junctions},
      journal = {Phys. Rev. B},
      publisher = {American Physical Society},
      year = {2013},
      volume = {87},
      number = {1},
      pages = {014114--},
      doi = {http://dx.doi.org/10.1103/PhysRevB.87.014114}
    }
    
    Satyendra Singh Chauhan, Pankaj Srivastava & A.K. Shrivastava Effect of Vacancy on Electronic and Transport Properties of Graphene Nanoribbons: An Ab Initio Approach 2012 Journal of Computational and Theoretical Nanoscience
    Vol. 9(12), 2215-2216 
    DOI  
    Abstract: We report a spin-unpolarized density functional theory study of electronic and transport properties of zigzag graphene nanoribbons (ZGNRs) defected with one and two vacancy atoms. The pristine and vacancy defected structures of 8 ZGNRs are found to be metallic. The one atom vacancy ZGNRs is energetically more stable. The localized states appear when there are vacancies inside the ZGNRs, which affects its transmission. In case of two vacancies in the ZGNRs the additional peak in DOS is observed close to the Fermi level and the transmission decreases further. Hence, our results point towards the relative suitability of these materials in nanoelectronics applications.
    Keywords: ATK; Application; graphene nanoribbons; stability; electronic; transport; metallic; defect
    Area: graphene
    BibTeX:
    @article{Chauhan2012a,
      author = {Chauhan, Satyendra Singh and Srivastava, Pankaj and Shrivastava, A.K.},
      title = {Effect of Vacancy on Electronic and Transport Properties of Graphene Nanoribbons: An Ab Initio Approach},
      journal = {Journal of Computational and Theoretical Nanoscience},
      year = {2012},
      volume = {9},
      number = {12},
      pages = {2215--2216},
      doi = {http://dx.doi.org/10.1166/jctn.2012.2641}
    }
    
    Ming-Jun Li, Meng-Qiu Long, Ke-Qiu Chen & Hui Xu Fluorination effects on the electronic transport properties of dithiophene-tetrathiafulvalene (DT-TTF) molecular junctions 2013 Solid State Communications
    Vol. 157(0), 62-67 
    DOI  
    Abstract: The fluorination of dithiophene-tetrathiafulvalent (DT-TTF) was investigated by using the density functional theory combined with nonequilibrium Green's function method. It is demonstrated that fluorination can modify the electronic transport properties of DT-TTF. Negative differential resistance can be observed within a certain bias voltage range in 4FDT-TTF.
    Keywords: ATK; Application; molecular electronics; dithiophene-tetrathiafulvalene; fluorination effect; transport property; NDR behavior; negative differential resistance; field-effect transistors; intermolecular interaction; high-performance; high-mobility; metal-ions; ab-initio; devices; 1st-principles; wires
    Area: molecular electronics
    BibTeX:
    @article{Li2013,
      author = {Li, Ming-Jun and Long, Meng-Qiu and Chen, Ke-Qiu and Xu, Hui},
      title = {Fluorination effects on the electronic transport properties of dithiophene-tetrathiafulvalene (DT-TTF) molecular junctions},
      journal = {Solid State Communications},
      year = {2013},
      volume = {157},
      number = {0},
      pages = {62--67},
      doi = {http://dx.doi.org/10.1016/j.ssc.2012.12.001}
    }
    
    Hongmei Liu, Hongbo Wang, Jianwei Zhao & Manabu Kiguchi Molecular rectification in triangularly shaped graphene nanoribbons 2013 J. Comput. Chem.
    Vol. 34(5), 360-365 
    DOI  
    Abstract: We present a theoretical study of electron transport in tailored zigzag graphene nanoribbons (ZGNRs) with triangular structure using density functional theory together with the nonequilibrium Green's function formalism. We find significant rectification with a favorite electron transfer direction from the vertex to the right edge. The triangular ZGNR connecting to the electrode with one thiol group at each terminal shows an average rectification ratio of 8.4 over the bias range from -1.0 to 1.0 V. This asymmetric electron transport property originates from nearly zero band gap of triangular ZGNR under negative bias, whereas a band gap opens under positive bias. When the molecule is connected to the electrode by multithiol groups, the current is enhanced due to strong interfacial coupling; however, the rectification ratio decreases. The simulation results indicate that the unique electronic states of triangular ZGNR are responsible for rectification, rather than the asymmetric anchoring groups.
    Keywords: ATK; Application; triangular graphene nanoribbon; molecular rectification; band gap; electron transport; quantum-interference; electron-transport; wire junctions; conductance; resistance; nanodisk; contact; formula
    Area: graphene
    BibTeX:
    @article{Liu2013,
      author = {Liu, Hongmei and Wang, Hongbo and Zhao, Jianwei and Kiguchi, Manabu},
      title = {Molecular rectification in triangularly shaped graphene nanoribbons},
      journal = {J. Comput. Chem.},
      publisher = {Wiley Subscription Services, Inc., A Wiley Company},
      year = {2013},
      volume = {34},
      number = {5},
      pages = {360--365},
      doi = {http://dx.doi.org/10.1002/jcc.23142}
    }
    
    M. Qiu & K.M. Liew Length dependence of carbon-doped BN nanowires: A-D Rectification and a route to potential molecular devices 2013 Journal of Applied Physics
    Vol. 113(5), 054305 
    DOI  
    Abstract: Based on the first-principles approach, electronic transport properties of different lengths of carbon-doped boron-nitrogen nanowires, capped with two thiols as end groups connected to Au electrodes surfaces, are investigated. The results show that rectifying performance and negative differential resistance (NDR) behaviors can be enhanced obviously by increasing the length. Analysis of Mülliken population, transmission spectra, evolutions of frontier orbitals and molecular projected self-consistent Hamiltonian of molecular orbital indicate that electronic transmission strength, charge transfer and distributions of molecular states change are the intrinsic origin of these rectifying performances and NDR behaviors.
    Keywords: ATK; Application; wide band gap semiconductors; boron-nitride; doping; negative differential resistance; NDR
    Area: molecular electronics; nanowires
    BibTeX:
    @article{Qiu2013,
      author = {Qiu, M. and Liew, K. M.},
      title = {Length dependence of carbon-doped BN nanowires: A-D Rectification and a route to potential molecular devices},
      journal = {Journal of Applied Physics},
      publisher = {AIP},
      year = {2013},
      volume = {113},
      number = {5},
      pages = {054305},
      doi = {http://dx.doi.org/10.1063/1.4790306}
    }
    
    Hari Mohan Rai, Neeraj K. Jaiswal, Pankaj Srivastava & Rajnish Kurchania Electronic and Transport Properties of Zigzag Boron Nitride Nanoribbons 2013 Journal of Computational and Theoretical Nanoscience
    Vol. 10(2), 368-375 
    DOI  
    Abstract: We have systematically investigated the electronic and transport properties of bare and hydrogenated zigzag boron nitride nanoribbons (ZBNNRs). We employed the spin unrestricted density functional theory (DFT) calculations within the local spin density approximation (LSDA) to reveal the semi-metallicity in bare ZBNNRs. Both-edges H-termination turns the ribbons semiconducting. Moreover, the band gap of both-edges H-terminated ZBNNRs is inversely proportional to the ribbon width. Interestingly, only boron edge H-passivated ZBNNRs leads to semi-metallic character whereas only nitrogen edge H-termination exhibits semiconducting behavior. The breaking of degeneracy for up spin and down spin electrons, as observed in bare and one edge H-terminated ZBNNRs points towards the possibility of spin polarized current. The transmission spectrum (TS) analysis also confirms the separation of spin up and down electrons making ZBNNR a suitable candidate for spin filter devices and other spintronics applications.
    Keywords: ATK; Application; boron nitride nanoribbons; spin; band structures; density of states; transmission spectra
    Area: graphene; spin
    BibTeX:
    @article{Rai2013,
      author = {Rai, Hari Mohan and Jaiswal, Neeraj K. and Srivastava, Pankaj and Kurchania, Rajnish},
      title = {Electronic and Transport Properties of Zigzag Boron Nitride Nanoribbons},
      journal = {Journal of Computational and Theoretical Nanoscience},
      year = {2013},
      volume = {10},
      number = {2},
      pages = {368--375},
      doi = {http://dx.doi.org/10.1166/jctn.2013.2706}
    }
    
    S Barzilai, F Tavazza & L E Levine The effect of internal impurities on the mechanical and conductance properties of gold nanowires during elongation 2013 Modelling and Simulation in Materials Science and Engineering
    Vol. 21(2), 025004- 
    DOI  
    Abstract: The conductance and mechanical properties of contaminated gold nanowires (NWs) were studied using first principle calculations. Nanowires containing internal impurities of H 2 O or O 2 were elongated along two different directions. It was found that both impurities interact with the gold atoms and affect the properties of the NWs. From a mechanical viewpoint, the impurities increase the bond strength in their vicinity and, throughout the entire elongation, remain surrounded by gold atoms. The impurities do not migrate to the surface and never end up in the single atom chain. The NW fracture always occurs at an Au-Au bond, far from the impurity. Therefore, the impurities do not affect the fracture strength but do decrease the strain at fracture. A variety of conductance effects were observed depending on the type and location of the impurity, and the O 2 has the most significant impact. The O 2 reduces the conductance when it is close to the gold atoms in the main pathway. However, at the late stages of the elongation, both impurities are located far from the main pathway and have little influence on the conductance.
    Keywords: ATK; ATK-SE; Application; nanowire; mechanical properties; deformation; plasticity; defects; structural failure; quantum wire; nanowire; atomic wire; nanowire;
    Area: nanowires
    BibTeX:
    @article{Barzilai2013,
      author = {Barzilai, S and Tavazza, F and Levine, L E},
      title = {The effect of internal impurities on the mechanical and conductance properties of gold nanowires during elongation},
      journal = {Modelling and Simulation in Materials Science and Engineering},
      year = {2013},
      volume = {21},
      number = {2},
      pages = {025004--},
      doi = {http://dx.doi.org/10.1088/0965-0393/21/2/025004}
    }
    
    Yukihito Matsuura Current rectification in nickelocenylferrocene sandwiched between two gold electrodes 2013 J. Chem. Phys.
    Vol. 138(1), 014311-4 
    DOI  
    Abstract: I present a theoretical study of the electronic transport properties of nickelocenylferrocene sandwiched between gold electrodes. Compared with the biferrocene system, the nickelocenylferrocene system had high electrical conduction and rectification in the bias range -1 to 1 V. Furthermore, the spin-down states of the nickelocenylferrocene system exhibited perfect spin-filtering properties. From the electronic states of the nickelocenylferrocene, it was found that the rectification was caused by a difference in the bias-dependent behaviors between the Fe 3d and Ni 3d orbitals.
    Keywords: electrical conductivity, nickel compounds, organic compounds, rectification, ATK, Application, spin
    Area: molecular electronics; spin
    BibTeX:
    @article{Matsuura2013,
      author = {Matsuura, Yukihito},
      title = {Current rectification in nickelocenylferrocene sandwiched between two gold electrodes},
      journal = {J. Chem. Phys.},
      publisher = {AIP},
      year = {2013},
      volume = {138},
      number = {1},
      pages = {014311--4},
      doi = {http://dx.doi.org/10.1063/1.4773404}
    }
    
    Haiqing Wan, Benhu Zhou, Wenhu Liao & Guanghui Zhou Spin-filtering and rectification effects in a Z-shaped boron nitride nanoribbon junction 2013 The Journal of Chemical Physics
    Vol. 138(3), 034705 
    DOI URL 
    Abstract: A Z-shaped junction constructed by a few-nanometer-long armchair-edged boron nitride nanoribbon (ABNNR) sandwiched between two semi-infinite zigzag-edged BNNR electrodes with different hydrogen-passivated edge treatment is proposed, and its spin-dependent electronic transport is studied by ab initio calculations. It is found that a short ABNNR exhibits metallic behavior and can be used as a conduction channel. Interestingly, the spin-filtering and rectification effects exist in the junctions without any edge passivation or with boron-edge passivation. The analysis on the projected density of states and spatial distribution of molecular projected self-consistent Hamiltonian eigenstates gives an insight into the observed results for the system. Our results suggest that a BNNR-based nanodevices with spin-filtering and rectification effects may be synthesized from an hexagonal boron nitride sheet by properly tailoring and edge passivation.
    Keywords: ATK; Application; ab initio calculations; boron compounds; electrodes; electronic density of states; III-V semiconductors; nanoribbons; passivation; rectification; SCF calculations; wide band gap semiconductors; molecular rectifiers; graphene; transport; edges
    Area: graphene
    BibTeX:
    @article{Wan2013,
      author = {Haiqing Wan and Benhu Zhou and Wenhu Liao and Guanghui Zhou},
      title = {Spin-filtering and rectification effects in a Z-shaped boron nitride nanoribbon junction},
      journal = {The Journal of Chemical Physics},
      publisher = {AIP},
      year = {2013},
      volume = {138},
      number = {3},
      pages = {034705},
      url = {http://link.aip.org/link/?JCP/138/034705/1},
      doi = {http://dx.doi.org/10.1063/1.4775841}
    }
    
    Neng-Ping Wang & Xiao-Jun Xu Effects of defects near source or drain contacts of carbon nanotube transistors 2012 EPL (Europhysics Letters)
    Vol. 100(4), 47009- 
    DOI URL 
    Abstract: We calculate the amplitude of the random-telegraph-signal (RTS) noise due to a single charged defect in a long-channel p-type carbon nanotube field-effect transistor, using the nonequilibrium Green function method in a tight-binding approximation. We find that the amplitude of the RTS noise caused by a positive charge close to the source (or drain) contact increases with the applied gate voltage and drain voltage. A positive charge located at the nanotube-oxide interface and close to the source (or drain) contact may cause a large RTS noise of about 50% in the on-state.
    Keywords: Application; ATK-SE; field-effect transistors; random-telegraph-signal; low-frequency noise; 1/f noise; fluctuations; interface
    Area: nanotubes
    BibTeX:
    @article{Wang2012c,
      author = {Wang, Neng-Ping and Xu, Xiao-Jun},
      title = {Effects of defects near source or drain contacts of carbon nanotube transistors},
      journal = {EPL (Europhysics Letters)},
      year = {2012},
      volume = {100},
      number = {4},
      pages = {47009--},
      url = {http://stacks.iop.org/0295-5075/100/i=4/a=47009},
      doi = {http://dx.doi.org/10.1209/0295-5075/100/47009}
    }
    
    Jiaxin Zheng, Chengyong Xu, Lu Wang, Qiye Zheng, Hong Li, Qihang Liu, Ruge Quhe, Zhengxiang Gao, Junjie Shi & Jing Lu Sign-changeable spin-filter efficiency in linear carbon atomic chain 2013 Physica E: Low-dimensional Systems and Nanostructures
    Vol. 48(0), 101-105 
    DOI URL 
    Abstract: It is well known that there is spin-filter efficiency (SFE) of a linear carbon atomic chain. In this article, we examine the quantum transport calculations of a linear carbon atomic chain connected to two half-planar graphene electrodes by using the first-principle method and reveal for the first time that sign of the SFE of such carbon atomic chain is changeable with the bias. This makes the carbon atomic chains attractive to potential application of spintronics.
    Keywords: ATK; Application; graphene; molecular electronics; atomic chain; spin filter;
    Area: molecular electronics; graphene; spin
    BibTeX:
    @article{Zheng2013,
      author = {Zheng, Jiaxin and Xu, Chengyong and Wang, Lu and Zheng, Qiye and Li, Hong and Liu, Qihang and Quhe, Ruge and Gao, Zhengxiang and Shi, Junjie and Lu, Jing},
      title = {Sign-changeable spin-filter efficiency in linear carbon atomic chain},
      journal = {Physica E: Low-dimensional Systems and Nanostructures},
      year = {2013},
      volume = {48},
      number = {0},
      pages = {101--105},
      url = {http://www.sciencedirect.com/science/article/pii/S1386947712004778},
      doi = {http://dx.doi.org/10.1016/j.physe.2012.12.009}
    }
    
    Satyendra Singh Chauhan, Pankaj Srivastava & A.K. Shrivastava Band gap engineering in doped graphene nanoribbons: An ab initio approach 2013 Solid State Communications
    Vol. 154(0), 69-71 
    DOI URL 
    Abstract: We present first principle study for stability and electronic properties of armchair graphene nanoribbons (AGNRs). We have investigated the stability and electronic properties of armchair graphene nanoribbons whose edges are doped with (i) s-type elements, Mg (ii) p-type elements, B and S, and (iii) 3d-type TMs, Ti and Mn, atoms using density functional theory. We predict that transition metals as substitutional dopant in AGNRs are energetically more favorable and minimize the band gap. The edges of the AGNRs are chemically more active and they can accommodate appropriate dopants to obtain different electronic properties having the same geometrical structure of the ribbon. Our results suggest that such materials can be used for nanoelectronic and spintronic applications.
    Keywords: ATK, Application, graphene nanoribbons, density functional theory, stability, band gap
    Area: graphene
    BibTeX:
    @article{Chauhan2013,
      author = {Chauhan, Satyendra Singh and Srivastava, Pankaj and Shrivastava, A.K.},
      title = {Band gap engineering in doped graphene nanoribbons: An ab initio approach},
      journal = {Solid State Communications},
      year = {2013},
      volume = {154},
      number = {0},
      pages = {69--71},
      url = {http://www.sciencedirect.com/science/article/pii/S0038109812005832},
      doi = {http://dx.doi.org/10.1016/j.ssc.2012.10.030}
    }
    
    Sudhanshu Choudhary & S. Qureshi Theoretical study on the effect of dopant positions and dopant density on transport properties of a BN co-doped SiC nanotube 2013 Physics Letters A
    Vol. 377(5), 430-435 
    DOI URL 
    Abstract: We investigate the effect of dopant (boron 'B' - nitrogen 'N') position and density on electronic transport properties of a BN co-doped silicon carbide nanotube (SiCNT). The results show an increase in conductance when both BN impurities are far in space from each other. Orbital delocalization and appearance of new electronic states around Fermi level contribute to the current when this spacing is increased. On the other hand, a reduction in SiCNT conductivity was observed when BN dopant density was increased. This is attributed to the electronic states moving away from the Fermi level and orbital localization at higher bias voltages.
    Keywords: ATK; Application; ab initio; DFT; NEGF; SiCNT; nanotubes; doping; silicon-carbide nanotubes; electron-transport
    Area: nanotubes
    BibTeX:
    @article{Choudhary2013,
      author = {Choudhary, Sudhanshu and Qureshi, S.},
      title = {Theoretical study on the effect of dopant positions and dopant density on transport properties of a BN co-doped SiC nanotube},
      journal = {Physics Letters A},
      year = {2013},
      volume = {377},
      number = {5},
      pages = {430--435},
      url = {http://www.sciencedirect.com/science/article/pii/S0375960112012753},
      doi = {http://dx.doi.org/10.1016/j.physleta.2012.12.007}
    }
    
    X.J. Tan, H.J. Liu, J. Wei, J. Shi, X.F. Tang & C. Uher Thermoelectric properties of small diameter carbon nanowires 2013 Carbon
    Vol. 53(0), 286-291 
    URL 
    Abstract: The room temperature thermoelectric properties of three kinds of small diameter carbon nanowires are investigated by using nonequilibrium Green's function method and molecular dynamics simulations. Due to very low thermal conductance and a relatively high power factor, these nanowires are found to exhibit better thermoelectric performance than other low-dimensional carbon-based materials such as carbon nanotubes. Moreover, the ZT values of these systems can be further increased to about 10 by partial passivation of hydrogen, which greatly reduces both the electron and phonon contributions to the thermal conductance, but leaves the power factor less affected.
    Keywords: ATK; Application; carbon nanowire; thermoelectric properties; ZT; passivation; thermal conductance; nonequilibrium molecular-dynamics; thermal conductivity; nanowires; simulation; nanotubes; figure; merit of performance; metals
    Area: nanowires; thermo
    BibTeX:
    @article{Tan2013,
      author = {Tan, X.J. and Liu, H.J. and Wei, J. and Shi, J. and Tang, X.F. and Uher, C.},
      title = {Thermoelectric properties of small diameter carbon nanowires},
      journal = {Carbon},
      year = {2013},
      volume = {53},
      number = {0},
      pages = {286--291},
      url = {http://www.sciencedirect.com/science/article/pii/S0008622312008731}
    }
    
    X.Z. Wu, J. Xiao, L.N. Chen, C. Cao, H. Xu & M.Q. Long The effect of asymmetrical electrode on the transport properties of molecular devices 2013 Physica B: Condensed Matter
    Vol. 411(0), 131-135 
    DOI URL 
    Abstract: By applying nonequilibrium Green's functions in combination with the density functional theory, we have investigated the electronic transport properties of molecular devices consisting of the carbon atomic chain coupling with symmetry and asymmetry Au electrodes. The asymmetry Au electrodes systems display good rectifying behavior. The main origin of this phenomenon is that a molecular core coupling with asymmetry electrodes can generate two asymmetrical Schottky barriers at both extended molecule regions. This rectification is also explained by the calculated transmission spectrum and the spatial distribution of the LUMO and HOMO states.
    Keywords: Transport properties, Molecular device, Rectifying behavior, Asymmetry electrode, atomic chain, ATK, Application
    Area: molecular electronics
    BibTeX:
    @article{Wu2013,
      author = {Wu, X.Z. and Xiao, J. and Chen, L.N. and Cao, C. and Xu, H. and Long, M.Q.},
      title = {The effect of asymmetrical electrode on the transport properties of molecular devices},
      journal = {Physica B: Condensed Matter},
      year = {2013},
      volume = {411},
      number = {0},
      pages = {131--135},
      url = {http://www.sciencedirect.com/science/article/pii/S0921452612010241},
      doi = {http://dx.doi.org/10.1016/j.physb.2012.11.028}
    }
    
    Penchalaiah Palla & J.P. Raina Effect of Hexagonal Boron Nitride on Energy Band Gap of Graphene Antidot Structures 2012 Innovative Systems Design and Engineering
    Vol. 3(12), 27-39 
    URL 
    Abstract: The zero band gap (Eg) graphene becomes narrow Eg semiconductor when graphene is patterned with periodic array of hexagonal shaped antidots, the resultant is the hexagonal Graphene Antidot Lattice (hGAL). Based on the number of atomic chains between antidots, hGALs can be even and odd. The even hGALs (ehGAL) are narrow Eg semiconductors and odd hGALs (ohGAL) are semi-metals. The Eg opening up by hGALs is not sufficient to operate a realistic switching transistor. Also hGAL transistors realized on Si/SiO2 substrate are suffering with low carrier mobility and ON-OFF current ratio. In order to achieve a sizable Eg with good mobility, AB Bernal stacked hGALs on hexagonal Boron Nitride (hBN), ABA Bernal stacked hBN / hGAL / hBN sandwiched structures and AB misaligned hGAL /hBN structures are reported here for the first time. Using the first principles method the electronic structure calculations are performed. A sizable Eg of about 1.04 eV (940+100 meV ) is opened when smallest neck width medium radius ehGAL supported on hBN and about 1.1 eV (940 + 200 meV ) is opened when the same is sandwiched between hBN layers. A band gap on the order of 71 meV is opened for Bernal stacked ohGAL / hBN and nearly 142 meV opened for hBN / ohGAL /hBN structures for smallest radius and width of nine atomic chains between antidots. Unlike a misaligned graphene on hBN, the misaligned ohGAL/hBN structure shows increased Eg. This study could open up new ways of band gap engineering for graphene based nanostructures.
    Keywords: ATK-SE, ATK, Application, Graphene, graphene antidots, hexagonal boron nitride, band structure, band gap engineering
    Area: graphene
    BibTeX:
    @article{Palla2012,
      author = {Penchalaiah Palla and J.P. Raina},
      title = {Effect of Hexagonal Boron Nitride on Energy Band Gap of Graphene Antidot Structures},
      journal = {Innovative Systems Design and Engineering},
      year = {2012},
      volume = {3},
      number = {12},
      pages = {27-39},
      url = {http://www.iiste.org/Journals/index.php/ISDE/article/view/3653}
    }
    
    Zhi-Qiang Fan, Zhen-Hua Zhang, Xiao-Qing Deng, Gui-Ping Tang & Ke-Qiu Chen Reversible switching in an N-salicylideneaniline molecular device induced by hydrogen transfer 2012 Organic Electronics
    Vol. 13(12), 2954-2958 
    DOI  
    Abstract: By applying nonequilibrium Green's functions in combination with the density-functional theory, we investigate the electronic transport properties of an N-salicylideneaniline molecule sandwiched between two Au electrodes. The results show that the currents between the enol and keto tautomeric forms of the molecule vary widely and a reversible switching behavior can be found in this device due to the photoinduced hydrogen transfer. In addition, the current switching ratio which is a typical character of switching behavior will lower a little when an electron-donating group (-NH2) substitutes the right end hydrogen atom of the N-salicylideneaniline molecule. However, the substituent of an electron-withdrawing group (-NO2) on the same site can enlarge the current switching ratio two orders of magnitude, which greatly improve the potential of the N-salicylideneaniline molecular device in future logic and memory.
    Keywords: Molecular device, Electronic transport, Switching behavior, ATK, Application
    Area: molecular electronics
    BibTeX:
    @article{Fan2012c,
      author = {Fan, Zhi-Qiang and Zhang, Zhen-Hua and Deng, Xiao-Qing and Tang, Gui-Ping and Chen, Ke-Qiu},
      title = {Reversible switching in an N-salicylideneaniline molecular device induced by hydrogen transfer},
      journal = {Organic Electronics},
      year = {2012},
      volume = {13},
      number = {12},
      pages = {2954--2958},
      doi = {http://dx.doi.org/10.1016/j.orgel.2012.08.019}
    }
    
    Mausumi Chattopadhyaya, Md. Mehboob Alam, Sabyasachi Sen & Swapan Chakrabarti Electrostatic Spin Crossover and Concomitant Electrically Operated Spin Switch Action in a Ti-Based Endohedral Metallofullerene Polymer 2012 Phys. Rev. Lett.
    Vol. 109(25), 257204- 
    DOI  
    Abstract: Herein, we predict that a 1D chain of Ti@C32-C2-Ti@C32 (TEMF) will act as a spin switch in the presence of an electric field. The spin resolved density of states analyses reveal that, surprisingly, both the low- and high-spin states of TEMF are half-metal; however, the metallic density of states comes from the opposite spin channels of the two spin states. More remarkably, it is found that the electric field driven spin crossover between the low and high state in TEMF is achievable at field strength 1.04 V/nm, which eventually leads to the realization of the first ever electrically operated spin switch device.
    Keywords: ATK; Application; molecular electronics; atomic chain; spin switch; fullerenes
    Area: molecular electronics; fullerenes; spin
    BibTeX:
    @article{Chattopadhyaya2012,
      author = {Chattopadhyaya, Mausumi and Alam, Md. Mehboob and Sen, Sabyasachi and Chakrabarti, Swapan},
      title = {Electrostatic Spin Crossover and Concomitant Electrically Operated Spin Switch Action in a Ti-Based Endohedral Metallofullerene Polymer},
      journal = {Phys. Rev. Lett.},
      publisher = {American Physical Society},
      year = {2012},
      volume = {109},
      number = {25},
      pages = {257204--},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.109.257204}
    }
    
    R.K. Ghosh, S. Bhattacharya & S. Mahapatra Physics-Based Band Gap Model for Relaxed and Strained [100] Silicon Nanowires 2012 Electron Devices, IEEE Transactions on
    Vol. 59(6)Electron Devices, IEEE Transactions on, 1765-1772 
    DOI  
    Abstract: In this paper, we propose a physics-based simplified analytical model of the energy band gap and electron effective mass in a relaxed and strained rectangular [100] silicon nanowires (SiNWs). Our proposed formulation is based on the effective mass approximation for the nondegenerate two-band model and 4 x 4 Lüttinger Hamiltonian for energy dispersion relation of conduction band electrons and the valence band heavy and light holes, respectively. Using this, we demonstrate the effect of the uniaxial strain applied along [100]-direction and a biaxial strain, which is assumed to be decomposed from a hydrostatic deformation along [001] followed by a uniaxial one along the [100]-direction, respectively, on both the band gap and the transport and subband electron effective masses in SiNW. Our analytical model is in good agreement with the extracted data using the extended-Hückel-method-based numerical simulations over a wide range of device dimensions and applied strain.
    Keywords: ATK-SE, Application, Analytical models, Dispersion, Effective mass, Photonic band gap, Silicon, Strain, Wires, deformation, electrons, elemental semiconductors, hydrostatics, nanowires, numerical analysis, silicon, Lüttinger Hamiltonian, Si, biaxial strain, conduction band electron, effective mass approximation, electron effective mass, energy band gap, energy dispersion relation, extended-Hückel-method-based numerical simulation, hydrostatic deformation, nondegenerate two-band model, physics-based band gap model, physics-based simplified analytical model, relaxed nanowire, strained nanowire, uniaxial strain effect, valence band heavy hole, valence band light hole, Band gap, effective mass, nanowires, size quantization, strain
    Area: semi
    BibTeX:
    @article{Ghosh2012,
      author = {Ghosh, R.K. and Bhattacharya, S. and Mahapatra, S.},
      title = {Physics-Based Band Gap Model for Relaxed and Strained [100] Silicon Nanowires},
      booktitle = {Electron Devices, IEEE Transactions on},
      journal = {Electron Devices, IEEE Transactions on},
      year = {2012},
      volume = {59},
      number = {6},
      pages = {1765--1772},
      doi = {http://dx.doi.org/10.1109/TED.2012.2190737}
    }
    
    Ram Krishna Ghosh, Sitangshu Bhattacharya & Santanu Mahapatra k.p based closed form energy band gap and transport electron effective mass model for [100] and [110] relaxed and strained Silicon nanowire 2013 Solid-State Electronics
    Vol. 80(0), 124-134 
    DOI URL 
    Abstract: In this paper, we address a physics based closed form model for the energy band gap (Eg) and the transport electron effective mass in relaxed and strained [1 0 0] and [1 1 0] oriented rectangular Silicon Nanowire (SiNW). Our proposed analytical model along [1 0 0] and [1 1 0] directions are based on the k.p formalism of the conduction band energy dispersion relation through an appropriate rotation of the Hamiltonian of the electrons in the bulk crystal along [0 0 1] direction followed by the inclusion of a 4 x Lüttinger Hamiltonian for the description of the valance band structure. Using this, we demonstrate the variation in Eg and the transport electron effective mass as function of the cross-sectional dimensions in a relaxed [1 0 0] and [1 1 0] oriented SiNW. The behaviour of these two parameters in [1 0 0] oriented SiNW has further been studied with the inclusion of a uniaxial strain along the transport direction and a biaxial strain, which is assumed to be decomposed from a hydrostatic deformation along [0 0 1] with the former one. In addition, the energy band gap and the effective mass of a strained [1 1 0] oriented SiNW has also been formulated. Using this, we compare our analytical model with that of the extracted data using the nearest neighbour empirical tight binding sp3d5s* method based simulations and has been found to agree well over a wide range of device dimensions and applied strain.
    Keywords: Silicon nanowire, Size quantization, Band gap, Effective mass, Strain, ATK-SE, Application
    Area: semi
    BibTeX:
    @article{Ghosh2013a,
      author = {Ghosh, Ram Krishna and Bhattacharya, Sitangshu and Mahapatra, Santanu},
      title = {k.p based closed form energy band gap and transport electron effective mass model for [100] and [110] relaxed and strained Silicon nanowire},
      journal = {Solid-State Electronics},
      year = {2013},
      volume = {80},
      number = {0},
      pages = {124--134},
      url = {http://www.sciencedirect.com/science/article/pii/S0038110112003516},
      doi = {http://dx.doi.org/10.1016/j.sse.2012.11.001}
    }
    
    Y. Al & H.L. Zhang Construction and Conductance Measurement of Single Molecule Junctions 2012 Acta Physico-chimica Sinica
    Vol. 28(10), 2237-2248 
    DOI  
    Abstract: Molecular electronics has become an important research field in the past decade, and molecular devices can be used as molecular wires, switches, rectifiers, and transistors etc. Construction of metal/molecule/metal (MMM) junctions is the most effective method for investigating the charge transport properties of molecular devices. However, the measurement of individual molecule junctions at the nanoscale is still very challenging because of many technical difficulties. This paper reviews the recent progress and the challenges in the measurement of single molecule conductance, and summarizes investigation of the charge transport mechanism.
    Keywords: atomic-force microscopy; walled carbon nanotubes; electronic devices; charge-transport; electrical conductance; quantum transport; metal nanowires; break junctions; scanning probe; spin; ATK; Application
    Area: molecular electronics
    BibTeX:
    @article{Al2012,
      author = {Al, Y. and Zhang, H. L.},
      title = {Construction and Conductance Measurement of Single Molecule Junctions},
      journal = {Acta Physico-chimica Sinica},
      publisher = {Peking Univ Press},
      year = {2012},
      volume = {28},
      number = {10},
      pages = {2237--2248},
      doi = {http://dx.doi.org/10.3866/PKU.WHXB201209102}
    }
    
    Sudhanshu Choudhary & S. Qureshi Effect of moisture on electron transport in SiC nanotubes: An ab-initio study 2012 Physics Letters A
    Vol. 376(45), 3359-3362 
    DOI URL 
    Abstract: We investigate the effect of moisture-adsorption on the electronic transport properties of a silicon-carbide nanotube (SiCNT). The results obtained by relaxing an H2O (water) molecule over an (8,0 ) SiCNT show that water molecule binds with SiCNT. The formation of SiO bond (bond length 1.95 Å) between the SiCNT and H2O molecule was discovered. However, previous studies on H2O adsorbtion in carbon nanotubes (CNTs) have shown the formation of CH bond at the CNT surface. Current-voltage (I-V) characteristics show a reduction in SiCNT conductivity when the number of H2O molecules over SiCNT were increased.
    Keywords: ATK; Application; sensor; ab-initio; DFT; NEGF; SiCNT; carbon nanotube;
    Area: nanotubes
    BibTeX:
    @article{Choudhary2012a,
      author = {Choudhary, Sudhanshu and Qureshi, S.},
      title = {Effect of moisture on electron transport in SiC nanotubes: An ab-initio study},
      journal = {Physics Letters A},
      year = {2012},
      volume = {376},
      number = {45},
      pages = {3359--3362},
      url = {http://www.sciencedirect.com/science/article/pii/S0375960112009693},
      doi = {http://dx.doi.org/10.1016/j.physleta.2012.08.052}
    }
    
    R.K. Ghosh & S. Mahapatra Direct Band-to-Band Tunneling in Reverse Biased MoS2 Nanoribbon p-n Junctions 2013 IEEE Transactions on Electron Devices
    Vol. 60(1), 274-279 
    DOI  
    Abstract: We investigate the direct band-to-band tunneling (BTBT) in a reverse biased molybdenum disulfide (MoS2) nanoribbon p-n junction by analyzing the complex band structure obtained from semiempirical extended Hückel method under relaxed and strained conditions. It is demonstrated that the direct BTBT is improbable in relaxed monolayer nanoribbon; however, with the application of certain uniaxial tensile strain, the material becomes favorable for it. On the other hand, the relaxed bilayer nanoribbon is suitable for direct BTBT but becomes unfavorable when the applied uniaxial tensile or compressive strain goes beyond a certain limit. Considering the Wentzel-Kramers-Brillouin approximation, we evaluate the tunneling probability to estimate the tunneling current for a small applied reverse bias. Reasonably high tunneling current in the MoS2 nanoribbons shows that it can take advantage over graphene nanoribbon in future tunnel field-effect transistor applications.
    Keywords: ATK-SE, Application, bandgap, band-to-band tunneling (BTBT), complex band structure, nanoribbon, strain, MoS2
    Area: graphene; dichalcogenides
    BibTeX:
    @article{Ghosh2013,
      author = {Ghosh, R. K. and Mahapatra, S.},
      title = {Direct Band-to-Band Tunneling in Reverse Biased MoS2 Nanoribbon p-n Junctions},
      journal = {IEEE Transactions on Electron Devices},
      year = {2013},
      volume = {60},
      number = {1},
      pages = {274-279},
      doi = {http://dx.doi.org/10.1109/TED.2012.2226729}
    }
    
    Yan-Dong Guo, Xiao-Hong Yan & Yang Xiao Computational Investigation of DNA Detection Using Single-Electron Transistor-Based Nanopore 2012 J. Phys. Chem. C
    Vol. 116(40)The Journal of Physical Chemistry C, 21609-21614 
    DOI  
    Abstract: We propose a single-electron transistor (SET)-based nanopore sensor for DNA sequencing, which consists of source, drain, and gate electrodes, as well as a nanopore where the DNA molecule is pulled through. For nanopore sensors based on transverse electronic transport, generally, the tunneling current is relatively small due to the weak coupling between the molecule and electrodes. We take full advantage of this feature by introducing SET to make the device operate in Coulomb-blockade regime. Through first-principles simulations, the charge stability diagrams of the nucleobases within the SET-nanopore environment are demonstrated to be distinctive for each molecule and, more importantly, independent of the nucleobase orientation, which can be served as electronic fingerprint for detection. We show that identifying the nucleobases can be achieved only though several specific regions or points in the diagram.
    Keywords: ATK; Application; single-electron transistor; set; sensor; dna sequencing; nucleoside; graphene nanopores; nucleotides; translocation; molecules; transport; capacitor; energies; device; holes; edge
    Area: molecular electronics; SET;
    BibTeX:
    @article{Guo2012a,
      author = {Guo, Yan-Dong and Yan, Xiao-Hong and Xiao, Yang},
      title = {Computational Investigation of DNA Detection Using Single-Electron Transistor-Based Nanopore},
      booktitle = {The Journal of Physical Chemistry C},
      journal = {J. Phys. Chem. C},
      publisher = {American Chemical Society},
      year = {2012},
      volume = {116},
      number = {40},
      pages = {21609--21614},
      doi = {http://dx.doi.org/10.1021/jp305909p}
    }
    
    Jun He & Ke-Qiu Chen Rectifying and perfect spin filtering behavior realized by tailoring graphene nanoribbons 2012 J. Appl. Phys.
    Vol. 112(11), 114319-5 
    DOI  
    Abstract: An armchair graphene nanoribbon based electronic device with spin filtering and rectifying behavior is designed by means of molecular tailoring, and the electronic transport properties are calculated by using nonequilibrium Green's functions in combination with the density functional theory. The results show that the rectifying behavior can be observed in the junctions, and the rectifying ratio can be effectively tuned by edge doping. Furthermore, perfect spin polarization behavior can also be observed in the junctions.
    Keywords: ATK, Application, density functional theory, fullerene devices, graphene, green's function methods, nanoelectronics, nanoribbons, rectification, spin polarised transport, field-effect transistors, transport-properties, room-temperature, heterojunctions
    Area: graphene; spin
    BibTeX:
    @article{He2012b,
      author = {He, Jun and Chen, Ke-Qiu},
      title = {Rectifying and perfect spin filtering behavior realized by tailoring graphene nanoribbons},
      journal = {J. Appl. Phys.},
      publisher = {AIP},
      year = {2012},
      volume = {112},
      number = {11},
      pages = {114319--5},
      doi = {http://dx.doi.org/10.1063/1.4768727}
    }
    
    Golam Rasul Ahmed Jamal & Md Shamsul Arefin Empirical Equation of Tight Binding Model Parameter to Calculate Bandgap of Semiconducting Single Wall Carbon Nanotube 2012 Journal of Electrical Engineering, The Institution of Engineers, Bangladesh
    Vol. 37(2), 3 
    URL 
    Abstract: Both Mod 1 and Mod 2 type semiconducting single wall carbon nanotubes over a wide diameter range are studied separately to find their band gap trend. For accurate calculation of their band gaps, modification of nearest-neighbor hopping parameter of the tight-binding model is proposed by considering it as a function of nanotube chiral index and mod value. A simple empirical equation for the nearest-neighbor hopping parameter is presented to produce band gaps of these nanotubes that agree well with simulated data. Empirical data are also compared with experimental data and found to be in excellent agreement with it after adding a flat correction.
    Keywords: ATK-SE; Application; tight-binding; carbon nanotube; band gap; nearest neighbor hopping parameter; tight-binding model; chiral index
    Area: nanotubes
    BibTeX:
    @article{Jamal2012,
      author = {Golam Rasul Ahmed Jamal and Md Shamsul Arefin},
      title = {Empirical Equation of Tight Binding Model Parameter to Calculate Bandgap of Semiconducting Single Wall Carbon Nanotube},
      journal = {Journal of Electrical Engineering, The Institution of Engineers, Bangladesh},
      year = {2012},
      volume = {37},
      number = {2},
      pages = {3},
      url = {http://www.banglajol.info/bd/index.php/JEE/article/view/12671}
    }
    
    Ahmed Mahmoud & Paolo Lugli Designing the rectification behavior of molecular diodes 2012 J. Appl. Phys.
    Vol. 112(11), 113720-5 
    DOI  
    Abstract: Thanks to major advances in chemical and fabrication processes, various electronic devices based on single molecules have been demonstrated. On the theoretical level, many attempts have been made to provide a clear view of the charge transport mechanism through molecules. However, the overall picture is not yet complete. In this study, we show that the rectification of a molecular device can be controlled by enforcing the potential drop profile along the molecule. The insertion of a resistive molecular path near the metallic electrode(s) can drastically alter the rectification behavior. Our observation paves the way for a better control of molecular devices.
    Keywords: ATK-SE; Application; diodes; molecular electronics; transport; nanostructures; protonation; inversion; device
    Area: molecular electronics
    BibTeX:
    @article{Mahmoud2012a,
      author = {Mahmoud, Ahmed and Lugli, Paolo},
      title = {Designing the rectification behavior of molecular diodes},
      journal = {J. Appl. Phys.},
      publisher = {AIP},
      year = {2012},
      volume = {112},
      number = {11},
      pages = {113720--5},
      doi = {http://dx.doi.org/10.1063/1.4768924}
    }
    
    Yukihito Matsuura Electron Transport in Polymeric µ-Cyclopentadienylelement Complexes of the Main Group Elements 2012 Molecular Crystals and Liquid Crystals
    Vol. 569(1)Molecular Crystals and Liquid Crystals, 103-111 
    DOI  
    Abstract: I examined electrical conduction in polymeric µ-cyclopentadienylelement (Cp-E) complexes of the main group elements using the nonequilibrium Green's function formalism with the density functional theory. The polymeric Cp-E complexes of group 1 elements, which had ionic Cp-E bonds, showed very low conductance. In contrast, the polymeric Cp-E complexes of groups 13 and 14 elements exhibited enhanced n-type electrical conduction when a bias was applied between the electrodes, because the delocalized electronic states of the lowest unoccupied molecular orbital were within the bias window.
    Keywords: ATK; Application; molecular electronics; cyclopentadienyl complex; DFT; electron transport; NEGF
    Area: molecular electronics
    BibTeX:
    @article{Matsuura2012a,
      author = {Matsuura, Yukihito},
      title = {Electron Transport in Polymeric µ-Cyclopentadienylelement Complexes of the Main Group Elements},
      booktitle = {Molecular Crystals and Liquid Crystals},
      journal = {Molecular Crystals and Liquid Crystals},
      publisher = {Taylor & Francis},
      year = {2012},
      volume = {569},
      number = {1},
      pages = {103--111},
      doi = {http://dx.doi.org/10.1080/15421406.2012.689575}
    }
    
    Fanben Meng, Yves-Marie Hervault, Lucie Norel, Karine Costuas, Colin Van Dyck, Victor Geskin, Jerome Cornil, Huey Hoon Hng, Stephane Rigaut & Xiaodong Chen Photo-modulable molecular transport junctions based on organometallic molecular wires 2012 Chem. Sci.
    Vol. 3(10), 3113-3118 
    DOI  
    Abstract: Photo-modulable molecular transport junctions are developed via on-wire lithography-fabricated nanogaps functionalized with a dithienylethene unit bearing two ruthenium fragments. A reversible and repeatable bi-state conductive switching upon alternate irradiation of UV and visible light can be distinctly observed. Theoretical calculations further suggest that bi-directional isomerization is due to the ruthenium moieties that modulate judiciously the electronic coupling between the photochromic part and the metal electrodes, and that the differences in electronic structure between the two isomers (open and closed states) are responsible for conductivity switching.
    Keywords: ATK; Application; scanning-tunneling-microscopy; different oxidation-states; carbon-rich bridges; theoretical investigations; conductance; electronics; complexes; devices; ruthenium; temperature
    Area: molecular electronics
    BibTeX:
    @article{Meng2012,
      author = {Meng, Fanben and Hervault, Yves-Marie and Norel, Lucie and Costuas, Karine and Van Dyck, Colin and Geskin, Victor and Cornil, Jerome and Hng, Huey Hoon and Rigaut, Stephane and Chen, Xiaodong},
      title = {Photo-modulable molecular transport junctions based on organometallic molecular wires},
      journal = {Chem. Sci.},
      publisher = {The Royal Society of Chemistry},
      year = {2012},
      volume = {3},
      number = {10},
      pages = {3113--3118},
      doi = {http://dx.doi.org/10.1039/C2SC20323E}
    }
    
    Huaping Xiao, Yuanping Chen, Yuee Xie, Tao Ouyang, Ye Zhang & Jianxin Zhong The modification of central B/N atom chain on electron transport of graphene nanoribbons 2012 J. Appl. Phys.
    Vol. 112(11), 113713-5 
    DOI  
    Abstract: The electronic transport properties of hybrid graphene nanoribbons constructed by substituting C atom chain into B (N) atom chain are investigated through using the density functional theory in combination with the nonequilibrium Green's function method. It is found that the hybrid nanoribbon with armchair edge transits from semiconducting to metallic. While the transport properties of hybrid B (N) system with zigzag edge are highly improved with the transmission conductance around the Fermi level increasing to 6G0 (5G0). All these unique transport properties are mainly attributed to the coupling effect between B (N) atoms and C atoms at the interface of hybrid systems, which introduces a pair of bonding and antibonding bands around the Fermi level. The results indicate that such hybrid system is an effective way to modulate the transport properties of graphene nanoribbons.
    Keywords: density functional theory, electrical conductivity transitions, Fermi level, graphene, Green's function methods, metal-insulator transition, nanoribbons, phase, ATK, Application
    Area: graphene
    BibTeX:
    @article{Xiao2012a,
      author = {Xiao, Huaping and Chen, Yuanping and Xie, Yuee and Ouyang, Tao and Zhang, Ye and Zhong, Jianxin},
      title = {The modification of central B/N atom chain on electron transport of graphene nanoribbons},
      journal = {J. Appl. Phys.},
      publisher = {AIP},
      year = {2012},
      volume = {112},
      number = {11},
      pages = {113713--5},
      doi = {http://dx.doi.org/10.1063/1.4768719}
    }
    
    Yuqing Xu, Bin Cui, Guomin Ji, Dongmei Li & Desheng Liu Effect of the orientation of nitro group on the electronic transport properties in single molecular field-effect transistors 2013 Phys. Chem. Chem. Phys.
    Vol. 15(3), 832-836 
    DOI  
    Abstract: Molecular devices with nitro groups display unique electronic transport properties in experiments. By applying the non-equilibrium Green's function combined with density functional theory, we find that the orientation of the nitro group with respect to the backbone of the molecule has a crucial effect on the device performance and can show unusual experimental phenomena. Furthermore, molecular devices with a nitro group are sensitive to gate voltage and suitable for making effective single molecular field-effect transistors. These results provide an important theoretical support to experiments and the design of future molecular devices by using nitro groups.
    Keywords: ATK; Application; molecular electronics; single molecular field-effect transistor; switch; quantum transport
    Area: molecular electronics
    BibTeX:
    @article{Xu2013,
      author = {Xu, Yuqing and Cui, Bin and Ji, Guomin and Li, Dongmei and Liu, Desheng},
      title = {Effect of the orientation of nitro group on the electronic transport properties in single molecular field-effect transistors},
      journal = {Phys. Chem. Chem. Phys.},
      publisher = {The Royal Society of Chemistry},
      year = {2013},
      volume = {15},
      number = {3},
      pages = {832--836},
      doi = {http://dx.doi.org/10.1039/C2CP41480E}
    }
    
    Wei Yao, K.L. Yao, G.Y. Gao, S.C. Zhu & H.H. Fu Anisotropic transport properties of zinc-blend ZnTe/CrTe heterogeneous junction nanodevices 2012 J. Appl. Phys.
    Vol. 112(10), 103717-6 
    DOI  
    Abstract: Motivated by the molecular-beam epitaxial growth of zinc-blend-type CrTe thin films on ZnTe, we present a theoretical study on the spin-polarized transport properties of ZnTe/CrTe p-n junction as spin diode and CrTe/ZnTe/CrTe magnetic tunnel junction for (001) and (011) surfaces. Both ZnTe(001)/CrTe(001) and ZnTe(011)/CrTe(011) p-n junctions show excellent spin diode effect, the majority spin current of positive voltage is much larger than that of negative voltage and the minority spin current is absolutely inhibited. The ZnTe(001)/CrTe(001) p-n junction has lower "turn off" current and higher rectification ratio (about 10^5) than the ZnTe(011)/CrTe(011) which shows obvious anisotropy. We also find that the tunneling magneto resistance ratio of the CrTe/ZnTe/CrTe magnetic tunnel junction is up to about 4x10^9%.
    Keywords: ATK, , Application, chromium compounds, diodes, electron spin polarisation, molecular beam epitaxial growth, nanotechnology, p-n junctions, thin films, tunnelling magnetoresistance, wide band gap semiconductors, zinc compounds, MTJ, half-metallic ferromagnets, molecular-beam epitaxy, room-temperature, spintronics, magnetoresistance, semiconductors
    Area: interfaces; nvm; semi; spin
    BibTeX:
    @article{Yao2012,
      author = {Yao, Wei and Yao, K. L. and Gao, G. Y. and Zhu, S. C. and Fu, H. H.},
      title = {Anisotropic transport properties of zinc-blend ZnTe/CrTe heterogeneous junction nanodevices},
      journal = {J. Appl. Phys.},
      publisher = {AIP},
      year = {2012},
      volume = {112},
      number = {10},
      pages = {103717--6},
      doi = {http://dx.doi.org/10.1063/1.4767935}
    }
    
    J. Yu, G.L. Zhang, Y. Shang, K.D. Wang, H. Zhang, M. Sun, B. Liu & T. Zeng Transport properties of CNT/oligosilane/CNT heterojunctions 2013 Physica B: Condensed Matter
    Vol. 410(0), 237-243 
    DOI  
    Abstract: Combining the non-equilibrium Green's function formalism with density functional theory, the transport properties of nine CNT/oligosilane/CNT heterojunctions were systematically studied. We have found that the incorporation of oligosilane linkage to the carbon nanotube mouth could significantly tune the transport properties compared with the pure oligosilane and pure CNT. The P- and B-dopings upon the oligosilane moiety could not only enhance the conductivity but also give rise to multiple negative differential resistance behavior for the CNT/oligosilane/CNT heterojunctions. The concentration of heteroatom plays an important role in the transport properties of the CNT/oligosilane/CNT heterojunctions, while the number of the oligosilane linkage exerts little effect on the conductivity. The B-doped CNT/oligosilane/CNT heterojunctions show higher conductivity than those of the P-doped ones. The p-n junction caused by B- and P-codopings exhibits a rectifying effect and the rectification ratio is up to 7.19.
    Keywords: ATK; Application; theoretical study; transport property; carbon nanotube; oligosilane; doping; negative differential resistance; walled carbon nanotubes; silicon nanowire; peptide linkages; ab-initio; conductance; transistors; electrodes; molecules; diode
    Area: nanotubes
    BibTeX:
    @article{Yu2013,
      author = {Yu, J. and Zhang, G.L. and Shang, Y. and Wang, K.D. and Zhang, H. and Sun, M. and Liu, B. and Zeng, T.},
      title = {Transport properties of CNT/oligosilane/CNT heterojunctions},
      journal = {Physica B: Condensed Matter},
      year = {2013},
      volume = {410},
      number = {0},
      pages = {237--243},
      doi = {http://dx.doi.org/10.1016/j.physb.2012.11.016}
    }
    
    C.X. Zhang, Huaping Xiao, Chaoyu He, L. Xue, K.W. Zhang, L.Z. Sun & Jianxin Zhong Effects of contact oxidization on the transport properties of Au/ZGNR junctions 2012 Phys. Status Solidi RRL
    Vol. 6(12), 457-459 
    DOI  
    Abstract: The transport properties of the junction assembled by zigzag graphene nanoribbons (ZGNRs) and Au electrode (Au/ZGNR) are investigated using first-principles calculations. It is found that the Au/ZGNR junction behaves as a typical diode with Schottky barrier at the contact. Our results indicate that although the oxidization at the contact slightly influences the Schottky barrier, the I-V characteristic is effectively modulated. Such effect derives from the impact of the oxidization on the coupling between the ZGNRs and Au electrode.
    Keywords: ATK, Application, graphene nanoribbons, electronic transport, contact oxidization, gold electrodes, augmented-wave method, graphene nanoribbons, carbon nanotubes, electronics, oxide
    Area: graphene
    BibTeX:
    @article{Zhang2012g,
      author = {Zhang, C. X. and Xiao, Huaping and He, Chaoyu and Xue, L. and Zhang, K. W. and Sun, L. Z. and Zhong, Jianxin},
      title = {Effects of contact oxidization on the transport properties of Au/ZGNR junctions},
      journal = {Phys. Status Solidi RRL},
      publisher = {WILEY-VCH Verlag},
      year = {2012},
      volume = {6},
      number = {12},
      pages = {457--459},
      doi = {http://dx.doi.org/10.1002/pssr.201206409}
    }
    
    Yi-Peng An, Xinyuan Wei & Zhong-Qin Yang Improving electronic transport of zigzag graphene nanoribbons by ordered doping of B or N atoms 2012 Phys. Chem. Chem. Phys.
    Vol. 14(45), 15802-15806 
    DOI  
    Abstract: Using an ab initio method, we explored electronic structures and transport properties of zigzag graphene nanoribbons (ZGNRs) with ordered doping of B or N atoms. We find B or N atoms doping can increase significantly the conductance of the ZGNRs with an even number of zigzag chains due to additional conducting channels being induced and the breakdown of parity limitation. The higher the doping concentration, the larger the current amplification factor obtained. For the nanojunctions with one row B (or N) atoms, the current amplification factor can be larger when the doping position is near to the center, while for the junction with two rows, the trend is subtle due to the interactions between the two rows of B (or N) atoms. Negative differential resistive phenomena are found for the case of B doping at low concentrations and the case for N doping. The conductance of the ZGNR with odd numbers of zigzag chains can also be increased by doping of B or N atoms. More interestingly, the B or N doping can almost completely remove the even-odd effect on electronic transport of the ZGNRs. Our studies provide avenues to drastically improve the electronic transport of ZGNRs, helpful for graphene applications.
    Keywords: ATK; Application; doping; negative differential resistance; NDR; field-effect transistors
    Area: graphene
    BibTeX:
    @article{An2012c,
      author = {An, Yi-Peng and Wei, Xinyuan and Yang, Zhong-Qin},
      title = {Improving electronic transport of zigzag graphene nanoribbons by ordered doping of B or N atoms},
      journal = {Phys. Chem. Chem. Phys.},
      publisher = {The Royal Society of Chemistry},
      year = {2012},
      volume = {14},
      number = {45},
      pages = {15802--15806},
      doi = {http://dx.doi.org/10.1039/C2CP42123B}
    }
    
    L.N. Chen, C. Cao, X.Z. Wu, S.S. Ma, W.R. Huang & H. Xu Effects of partial hydrogenation on electronic transport properties in C60 molecular devices 2012 Solid State Communications
    Vol. 152(23), 2123-2127 
    DOI URL 
    Abstract: By using nonequilibrium Green's functions in combination with the density–function theory, we investigate electronic transport properties of molecular devices with pristine and partial hydrogenation. The calculated results show that the electronic transport properties of molecular devices can be modulated by partial hydrogenation. Interestingly, our results exhibit negative differential resistance behavior in the case of the imbalance H-adsorption in C60 molecular devices under low bias. However, negative differential resistance behavior cannot be observed in the case of the balance H-adsorption. A mechanism is proposed for the hydrogenation and negative differential resistance behavior.
    Keywords: ATK; Application; molecular device; transport property; hydrogenation; first-principles; fullerenes
    Area: molecular electronics;
    BibTeX:
    @article{Chen2012a,
      author = {Chen, L.N. and Cao, C. and Wu, X.Z. and Ma, S.S. and Huang, W.R. and Xu, H.},
      title = {Effects of partial hydrogenation on electronic transport properties in C60 molecular devices},
      journal = {Solid State Communications},
      year = {2012},
      volume = {152},
      number = {23},
      pages = {2123--2127},
      url = {http://www.sciencedirect.com/science/article/pii/S0038109812005315},
      doi = {http://dx.doi.org/10.1016/j.ssc.2012.09.011}
    }
    
    Guomin Ji, Yuqing Xu, Bin Cui, Changfeng Fang, Xiangru Kong, Dongmei Li & Desheng Liu Rectifying behaviors of an Au/(C20)2/Au molecular device induced by the different positions of gate voltage 2012 RSC Advances
    Vol. 2(30), 11349-11353 
    DOI  
    Abstract: The electronic transport properties of a gated Au/(C20)2/Au molecular device are studied using nonequilibrium Green's function in combination with density functional theory. The results show that different applied positions of the external transverse gate voltage can effectively tune the current-voltage (I-V) characteristic of molecular devices. Rectifying behaviors of the device can be realized when the gate voltage is applied asymmetrically on the left C20 molecule, and the rectification directions can also be modulated by the positive or negative value of the gate voltage. These results provide an important theoretical support to experiments and the design of a molecular rectifier.
    Keywords: ATK; Application; molecular electronics; fullerenes; rectification
    Area: molecular electronics; fullerenes
    BibTeX:
    @article{Ji2012a,
      author = {Ji, Guomin and Xu, Yuqing and Cui, Bin and Fang, Changfeng and Kong, Xiangru and Li, Dongmei and Liu, Desheng},
      title = {Rectifying behaviors of an Au/(C20)2/Au molecular device induced by the different positions of gate voltage},
      journal = {RSC Advances},
      publisher = {The Royal Society of Chemistry},
      year = {2012},
      volume = {2},
      number = {30},
      pages = {11349--11353},
      doi = {http://dx.doi.org/10.1039/C2RA21146G}
    }
    
    Antonio J. Mota, Luis Ávarez de Cienfuegos, Sara P. Morcillo, Noelia Fuentes, Delia Miguel, Salvador Rodríguez-Bolívar, Francisco M. Gómez-Campos, Diego J. Cárdenas & Juan M. Cuerva Thermally Driven Nanofuses Based on Organometallic Rotors 2012 ChemPhysChem
    Vol. 13(17), 3857-3865 
    DOI  
    Abstract: Molecular design of chromium arenes are theoretically studied as a model for the development of novel thermally-driven molecular fuses. This study correlates the switching event with a partial disconnection of the molecule from the metallic electrode mediated by changes in the conformational states of the molecule directed by external stimuli. Moreover, the reversibility of the process (the reconnection to the metallic electrode) is also considered for these systems when a reversal voltage pulse (reset) is applied. The energetic requirements of the on and off states are correlated with temperature through the Arrhenius equation. To carry out this study we performed density functional theory (DFT) calculations.
    Keywords: ATK, Application, arene complexes, aromatic compounds, density functional calculations, electron transport, molecular motors; single molecular conductance; density-functional theory; aqueous-solution; junctions; electronics; transport; exchange; behavior
    Area: molecular electronics; thermo
    BibTeX:
    @article{Mota2012,
      author = {Mota, Antonio J. and Ávarez de Cienfuegos, Luis and Morcillo, Sara P. and Fuentes, Noelia and Miguel, Delia and Rodríguez-Bolívar, Salvador and Gómez-Campos, Francisco M. and Cárdenas, Diego J. and Cuerva, Juan M.},
      title = {Thermally Driven Nanofuses Based on Organometallic Rotors},
      journal = {ChemPhysChem},
      publisher = {WILEY-VCH Verlag},
      year = {2012},
      volume = {13},
      number = {17},
      pages = {3857--3865},
      doi = {http://dx.doi.org/10.1002/cphc.201200544}
    }
    
    Anurag Srivastava & Neha Tyagi Structural and electronic properties of AlX (X=P, As, Sb) nanowires: Ab initio study 2012 Materials Chemistry and Physics
    Vol. 137(1), 103-112 
    DOI URL 
    Abstract: Present paper discusses the structural stability and electronic properties of AlX (X = P, As and Sb) nanowires in its linear, zigzag, ladder, square and hexagonal type atomic configurations. The structural optimization has been performed in self consistence manner by using generalized gradient approximation with revised Perdew, Burke and Ernzerhof type parameterization. The study observes that in all the three nanowires, the square shaped atomic configuration is the most stable one. The calculated electronic band structures and density of states profile confirms the semiconducting behaviour of linear and zigzag shaped nanowires of AlP, whereas for AlAs and AlSb nanowires are metallic. The ground state properties have also been analysed in terms of bond length, bulk modulus and pressure derivative for all the nanowires along with their bulk counterpart. The lower bulk modulus of all the linear shaped geometries of AlX nanowires in comparison to its bulk counterpart indicates softening of the material at reduced dimension.
    Keywords: ATK; Application; nanostructures; semiconductors; ab initio calculations; band-structure; electronic structure; zincblende semiconductors; III-V; energetics
    Area: nanowires
    BibTeX:
    @article{Srivastava2012f,
      author = {Srivastava, Anurag and Tyagi, Neha},
      title = {Structural and electronic properties of AlX (X=P, As, Sb) nanowires: Ab initio study},
      journal = {Materials Chemistry and Physics},
      year = {2012},
      volume = {137},
      number = {1},
      pages = {103--112},
      url = {http://www.sciencedirect.com/science/article/pii/S0254058412007572},
      doi = {http://dx.doi.org/10.1016/j.matchemphys.2012.08.046}
    }
    
    Christian Wagner, Jörg Schuster & Thomas Gessner DFT investigations of the piezoresistive effect of carbon nanotubes for sensor application 2012 Phys. Status Solidi B
    Vol. 249(12), 2450-2453 
    DOI  
    Abstract: We investigate the piezoresistive effect of carbon nanotubes (CNTs) within density functional theory (DFT) aiming at application-relevant CNTs. CNTs are excellent candidates for the usage in nano-electromechanical sensors (NEMSs) due to their small band gap at zero strain leading to a finite resistivity at room temperature. The application of strain induces a band gap-opening leading to a tremendous change in the resistivity. DFT with the LDA approximation yields reasonable results for pure carbon systems like CNTs and is applied to calculate the electronic structure of experimentally relevant CNTs. For the transport part, a simple ballistic transport model based on the band gap is used. We compare our DFT results for the band gaps of strained CNTs to results of tight binding (TB) models. By introducing a scaling factor of $sqrt 2 $, an excellent agreement of the DFT data with TB model, published by Yang and Han [Phys. Rev. Lett. 85, 154 (2000)], is obtained.
    Keywords: ATK, Application, acceleration sensor, bandgap, carbon nanotube, density functional theory, electronic structure, nanoelectronics, nanotechnology, piezoresistance
    Area: nanotubes
    BibTeX:
    @article{Wagner2012,
      author = {Wagner, Christian and Schuster, Jörg and Gessner, Thomas},
      title = {DFT investigations of the piezoresistive effect of carbon nanotubes for sensor application},
      journal = {Phys. Status Solidi B},
      publisher = {WILEY-VCH Verlag},
      year = {2012},
      volume = {249},
      number = {12},
      pages = {2450--2453},
      doi = {http://dx.doi.org/10.1002/pssb.201200113}
    }
    
    Bing Yang, Ruixin Dong, Xunling Yan & Qiang Shi Recognizing nucleosides with transverse electronic transport via perpendicular direction of base planes for DNA sequencing 2012 Nanoscale Research Letters
    Vol. 7(1), 512 
    DOI  
    Abstract: Putting the four DNA nucleosides in the middle of gold [111] nanoelectrodes with base planes parallel to the electrode surface layer, we study the transverse electronic transport properties of four nucleosides along the direction of electrodes. First, the optimal distance of the electrodes is released. The results show that the optimal electrode distance to study transverse electronic transport characteristics of DNA nucleosides is about 0.68 nm. Second, we theoretically calculate the conductance and current of the four nucleosides via perpendicular direction of base planes in the bias range of [2, 2] V by exploiting the first principle theory. According to the calculated results, we propose three methods to recognize the nucleoside type in practice application.
    Keywords: ATK; Application; DNA; nucleoside; electronic transport; DNA sequencing; nucleotides
    Area: molecular electronics
    BibTeX:
    @article{Yang2012c,
      author = {Yang, Bing and Dong, Ruixin and Yan, Xunling and Shi, Qiang},
      title = {Recognizing nucleosides with transverse electronic transport via perpendicular direction of base planes for DNA sequencing},
      journal = {Nanoscale Research Letters},
      year = {2012},
      volume = {7},
      number = {1},
      pages = {512},
      doi = {http://dx.doi.org/10.1186/1556-276X-7-512}
    }
    
    Wei Yao, K.L. Yao, G.Y. Gao, H.H. Fu & S.C. Zhu Boron-doping controlled peculiar transport properties of graphene nanoribbon p-n junctions 2013 Solid State Communications
    Vol. 153(1), 46-52 
    DOI URL 
    Abstract: We construct two kinds of p-n junctions based on graphene nanoribbons with different doping concentration. The left part of junction is Boron-doped at the edge of zigzag-edge graphene nanoribbon, and the right part is Boron-doped at the center. The transport properties, calculated by nonequilibrium Green's function method combined with the density functional theory under external bias, show obvious rectification effect and interesting negative differential resistance phenomenon depending on Boron-doping density and position. Considering the interaction of charge carriers with impurity and the correlation between charges at the edges and center, the excellent nanoscale electronic devices have been achieved.
    Keywords: ATK; Application; graphene nanoribbon; boron doping; diode effect; negative differential resistance; NDR
    Area: graphene
    BibTeX:
    @article{Yao2013,
      author = {Yao, Wei and Yao, K.L. and Gao, G.Y. and Fu, H.H. and Zhu, S.C.},
      title = {Boron-doping controlled peculiar transport properties of graphene nanoribbon p-n junctions},
      journal = {Solid State Communications},
      year = {2013},
      volume = {153},
      number = {1},
      pages = {46--52},
      url = {http://www.sciencedirect.com/science/article/pii/S0038109812005546},
      doi = {http://dx.doi.org/10.1016/j.ssc.2012.10.009}
    }
    
    Minggang Zeng, Wen Huang & Gengchiau Liang Spin-dependent thermoelectric effects in graphene-based spin valves 2013 Nanoscale
    Vol. 5(1), 200-208 
    DOI  
    Abstract: Using first-principles calculations combined with non-equilibrium Green's function (NEGF), we investigate spin-dependent thermoelectric effects in a spin valve which consists of zigzag graphene nanoribbon (ZGNR) electrodes with different magnetic configurations. We find that electron transport properties in the ZGNR-based spin valve are strongly dependent on the magnetic configurations. As a result, with a temperature bias, thermally-induced currents can be controlled by switching the magnetic configurations, indicating a thermal magnetoresistance (MR) effect. Moreover, based on the linear response assumption, our study shows that the remarkably different Seebeck coefficients in the various magnetic configurations lead to a very large and controllable magneto Seebeck ratio. In addition, we evaluate thermoelectric properties, such as the power factor, electron thermal conductance and figure of merit (ZT), of the ZGNR-based spin valve. Our results indicate that the power factor and the electron thermal conductance are strongly related to the transmission gap and electron-hole symmetry of the transmission spectrum. Moreover, the value of ZT can reach 0.15 at room temperature without considering phonon scattering. In addition, we investigate the thermally-controlled magnetic distributions in the ZGNR-based spin valve and find that the magnetic distribution, especially the local magnetic moment around the Ni atom, is strongly related to the thermal bias. The very large, multi-valued and controllable thermal magnetoresistance and Seebeck effects indicate the strong potential of ZGNR-based spin valves for extremely low-power consuming spin caloritronics applications. The thermally-controlled magnetic moment in the ZGNR-based spin valve indicates its possible applications for information storage.
    Keywords: ATK; Application; spin-dependent thermoelectric effects; spin valves; graphene; Seebeck; ZT; figure of merit; thermal magnetoresistance effect
    Area: graphene; spin; thermo
    BibTeX:
    @article{Zeng2013,
      author = {Zeng, Minggang and Huang, Wen and Liang, Gengchiau},
      title = {Spin-dependent thermoelectric effects in graphene-based spin valves},
      journal = {Nanoscale},
      publisher = {The Royal Society of Chemistry},
      year = {2013},
      volume = {5},
      number = {1},
      pages = {200--208},
      doi = {http://dx.doi.org/10.1039/C2NR32226A}
    }
    
    Daoli Zhang, Yuanlan Xu, Jianbing Zhang & Xiangshui Miao First-principles study of the electronic transport properties in (GaAs)n (n=2-4) nanocluster-based molecular junctions 2012 Physics Letters A
    Vol. 376(45), 3272-3276 
    DOI URL 
    Abstract: In this program the geometric structures and electronic transport properties of a series of (GaAs)n ( n = 2 , 3 , 4 ) clusters are comparatively studied using non-equilibrium Green's function (NEGF) combined with density functional theory (DFT). It is find that all the GaAs nanocluster-based molecular junctions show metallic behavior at low biases ([-2 V , 2 V]) while negative differential resistance (NDR) appears at a certain high bias range. Our calculation shows that the current of (GaAs)3 nanocluster-based molecular junction is almost the smallest at any bias. The mechanisms of the current-voltage characteristics of all the three molecular junctions are proposed.
    Keywords: ATK; Application; GaAs nanocluster; molecular device; negative differential resistance; NDR
    Area: molecular electronics
    BibTeX:
    @article{Zhang2012f,
      author = {Zhang, Daoli and Xu, Yuanlan and Zhang, Jianbing and Miao, Xiangshui},
      title = {First-principles study of the electronic transport properties in (GaAs)n (n=2-4) nanocluster-based molecular junctions},
      journal = {Physics Letters A},
      year = {2012},
      volume = {376},
      number = {45},
      pages = {3272--3276},
      url = {http://www.sciencedirect.com/science/article/pii/S037596011200998X},
      doi = {http://dx.doi.org/10.1016/j.physleta.2012.09.023}
    }
    
    Z.H. Zhang, C. Guo, G. Kwong & X.Q. Deng Electronic transport of nitrogen-capped monoatomic carbon wires between lithium electrodes 2013 Carbon
    Vol. 51(0), 313-321 
    DOI URL 
    Abstract: Nitrogen (N)-capped single-atom carbon wires are chemisorbed onto two identical Li (1 1 1) electrodes to construct nanodevices. First-principles calculations predict that devices with even and odd numbers of carbon wires would show dramatically different and unexpected electronic transport properties. An even number of wires shows a metallic-like ballistic transport at low bias, a nonlinear current-voltage characteristic over the whole bias region, and a very striking negative differential resistance (NDR). An odd number of carbon wires shows the exact opposite behavior. Currents are very small and rise extreme slowly with bias, and no NDR is observed. The zero-bias conductance of an even number of carbon wires is rather high and reaches a value of about 20 times larger than that for an odd number of wires. These intriguing phenomena can be attributed to changes in the molecular states due to charge transfer doping.
    Keywords: ATK; Application; negative differential resistance; NDR; molecular electronics;
    Area: molecular electronics
    BibTeX:
    @article{Zhang2013,
      author = {Zhang, Z.H. and Guo, C. and Kwong, G. and Deng, X.Q.},
      title = {Electronic transport of nitrogen-capped monoatomic carbon wires between lithium electrodes},
      journal = {Carbon},
      year = {2013},
      volume = {51},
      number = {0},
      pages = {313--321},
      url = {http://www.sciencedirect.com/science/article/pii/S0008622312007105},
      doi = {http://dx.doi.org/10.1016/j.carbon.2012.08.058}
    }
    
    Peng Zhao, De-Sheng Liu, Shu-Juan Li & Gang Chen Giant low bias negative differential resistance induced by nitrogen doping in graphene nanoribbon 2012 Chemical Physics Letters
    Vol. 554(0), 172-176 
    DOI URL 
    Abstract: By applying nonequilibrium Green's function formalism in combination with density functional theory, we have investigated the electronic transport properties of armchair graphene nanoribbon devices with periodic nitrogen-doping. Giant negative differential resistance behaviors with peak-to-valley ratio up to the order of 10^5 can be obtained in the mV bias regime by tuning the position and the concentration of the dopants. The negative differential resistance behavior is understood in terms of the evolution of the transmission spectrum and band structures with applied bias combined with the symmetry analyses of the Bloch wave functions of the corresponding subbands.
    Keywords: ATK; Application; graphene; doping;
    Area: graphene
    BibTeX:
    @article{Zhao2012i,
      author = {Zhao, Peng and Liu, De-Sheng and Li, Shu-Juan and Chen, Gang},
      title = {Giant low bias negative differential resistance induced by nitrogen doping in graphene nanoribbon},
      journal = {Chemical Physics Letters},
      year = {2012},
      volume = {554},
      number = {0},
      pages = {172--176},
      url = {http://www.sciencedirect.com/science/article/pii/S0009261412012109},
      doi = {http://dx.doi.org/10.1016/j.cplett.2012.10.045}
    }
    
    P. Zhao, D.S. Liu, S.J. Li & G. Chen Rectifying behavior in nitrogen-doped zigzag single-walled carbon nanotube junctions 2012 Solid State Communications
    Vol. 152(22), 2040-2044 
    DOI URL 
    Abstract: Using first-principles density functional theory and non-equilibrium Green's function formalism for quantum transport calculation, we have investigated the electronic transport properties of (8,0), (9,0) and (13,0) zigzag single-walled carbon nanotube junctions with one undoped and one nitrogen-doped zigzag carbon nanotube electrode. Our results show that the transport properties are strongly dependent on the magnitude of energy gap of carbon nanotube. Large rectifying behavior can be obtained in the junction with large energy gap. The observed rectifying behavior are explained in terms of the evolution of the transmission spectra and energy band structures with applied bias voltage combined with molecular projected self-consistent Hamiltonian eigenstates analysis.
    Keywords: ATK; Application; carbon nanotube; electronic transport; rectifying; negative differential resistance; transport-properties; devices; microtubules; conductance
    Area: nanotubes
    BibTeX:
    @article{Zhao2012j,
      author = {Zhao, P. and Liu, D.S. and Li, S.J. and Chen, G.},
      title = {Rectifying behavior in nitrogen-doped zigzag single-walled carbon nanotube junctions},
      journal = {Solid State Communications},
      year = {2012},
      volume = {152},
      number = {22},
      pages = {2040--2044},
      url = {http://www.sciencedirect.com/science/article/pii/S0038109812004784},
      doi = {http://dx.doi.org/10.1016/j.ssc.2012.08.013}
    }
    
    Wen-Kai Zhao, Chuan-Lu Yang, Mei-Shan Wang & Xiao-Guang Ma Effects of electrode orientation on the transport properties of pyridine-terminated dithienylethene light molecule switch under bias 2013 Solid State Communications
    Vol. 153(1), 1-7 
    DOI  
    Abstract: Prior to this work, the effects of the electrode orientation and the bias voltage on the pyridine-terminated dithienylethene molecules have not been investigated, although the switching effect of the molecules have been reported experimentally. Using the first-principles density-functional theory and nonequilibrium Green's function formalism, the present study examined the switching behaviors of open-ring and closed-ring forms of pyridine-terminated dithienylethene molecules between different crystallographic orientations of electrodes and under different bias voltages. The characteristics of I-V curves are investigated, and the negative differential resistance behavior is observed for the open-ring forms with different electrodes.
    Keywords: ATK; Application; molecular switch; electronic transport; negative differential resistance; ndr; generalized gradient approximation; nanowire building-blocks; field-effect transistors; quantum transport; logic gates; conductance; junctions; devices
    Area: molecular electronics
    BibTeX:
    @article{Zhao2013,
      author = {Zhao, Wen-Kai and Yang, Chuan-Lu and Wang, Mei-Shan and Ma, Xiao-Guang},
      title = {Effects of electrode orientation on the transport properties of pyridine-terminated dithienylethene light molecule switch under bias},
      journal = {Solid State Communications},
      year = {2013},
      volume = {153},
      number = {1},
      pages = {1--7},
      doi = {http://dx.doi.org/10.1016/j.ssc.2012.10.001}
    }
    
    Lin Zhu & Shiv N. Khanna Quantum spin transport through magnetic superatom dimer (Cs[sub 8]V-Cs[sub 8]V) 2012 J. Chem. Phys.
    Vol. 137(16), 164311-6 
    DOI  
    Abstract: Theoretical studies of the spin transport through a magnetic superatom dimer (Cs8V)-(Cs8V) have been carried out within a density functional theory combined with nonequilibrium Green's-function formalism. It is shown that the electronic transport is sensitive to the binding site as well as the contact distance between the dimer and the electrode, and that the conductance at zero bias exhibits an oscillatory behavior as a function of the contact distance. The conductance in ferromagnetic state shows an unusually high spin polarization that exceeds 80% at large separations. The I-V curve shows negative differential resistance for specific contact distances, whose origin lies in the shift of frontier energy levels as well as the charged state of the superatom, under external bias.
    Keywords: caesium alloys, contact resistance, density functional theory, electric admittance, ferromagnetic materials, Green's function methods, metal clusters, molecular magnetism, spin polarised transport, vanadium alloys, ATK, Application
    Area: molecular electronics; spin
    BibTeX:
    @article{Zhu2012a,
      author = {Zhu, Lin and Khanna, Shiv N.},
      title = {Quantum spin transport through magnetic superatom dimer (Cs[sub 8]V-Cs[sub 8]V)},
      journal = {J. Chem. Phys.},
      publisher = {AIP},
      year = {2012},
      volume = {137},
      number = {16},
      pages = {164311--6},
      doi = {http://dx.doi.org/10.1063/1.4763461}
    }
    
    Si-Cong Zhu, Kai-Lun Yao, Guo-Ying Gao & Yun Ni Spin-dependent transport in graphene nanoribbons adsorbed with vanadium in different positions 2013 Solid State Communications
    Vol. 155(0), 40-44 
    DOI URL 
    Abstract: The spin-polarized quantum transport properties of graphene nanoribbons (GNRs) adsorbed with vanadium atoms and terminated with hydrogen are investigated by density functional theory (DFT) associated with nonequilibrium Green's function theory (NGFT). The spin current behaves nonlinearly against bias voltage for the 4-zigzag graphene nanoribbons (ZGNRs), even changing signal at certain voltages due to specific features of the coupling between molecular states and magnetic leads; For the V-adsorbed 7-armchair graphene nanoribbons (ACGNRs), the transmission coefficients is dramatical large. All these results suggest that the present structures are suitable for nanoelectronics and spintronics applications.
    Keywords: ATK; Application; graphene nanoribbons; bias-current; nonlinearly; tunneling; spin; doping; dopant;
    Area: graphene; spin
    BibTeX:
    @article{Zhu2013,
      author = {Zhu, Si-Cong and Yao, Kai-Lun and Gao, Guo-Ying and Ni, Yun},
      title = {Spin-dependent transport in graphene nanoribbons adsorbed with vanadium in different positions},
      journal = {Solid State Communications},
      year = {2013},
      volume = {155},
      number = {0},
      pages = {40--44},
      url = {http://www.sciencedirect.com/science/article/pii/S0038109812006084},
      doi = {http://dx.doi.org/10.1016/j.ssc.2012.11.001}
    }
    
    A. Blom & K. Stokbro Towards realistic atomic-scale modeling of nanoscale devices 2011 Nanotechnology (IEEE-NANO), 2011 11th IEEE Conference on, 1487-1492  DOI  
    Abstract: On the nanoscale, electrical currents behave radically different compared to on the microscale. As the active regions become comparable to or smaller than the mean-free path of the material, it becomes necessary to describe the electron transport by quantum-mechanical methods instead of using classical relations like Ohm's law. Over the past decade, methods for computing electron tunneling currents in nanosized junctions have evolved steadily, and are now approaching a sophistication where they can provide real assistance in the development of novel semiconductor materials and devices. At the same time, the industry's demand for such solutions is rising rapidly to meet the challenges both above and under the 16 nm node. In this paper we provide an overview of the current state-of-the-art of the field of how to model electrical currents on the nanoscale, using atomic-scale simulations.
    Keywords: ATK, Application, Review, electron mobility, nanoelectronics, semiconductor device models, technology CAD (electronics), tunnelling, active regions, atomic-scale modeling, atomic-scale simulation, electron transport, electron tunneling current, nanoscale devices, nanoscale electrical currents, nanosized junctions, quantum-mechanical method, semiconductor device, semiconductor materials
    Area: molecular electronics; semi; graphene, nanotubes
    BibTeX:
    @inproceedings{Blom2011,
      author = {Blom, A. and Stokbro, K.},
      title = {Towards realistic atomic-scale modeling of nanoscale devices},
      booktitle = {Nanotechnology (IEEE-NANO), 2011 11th IEEE Conference on},
      year = {2011},
      pages = {1487--1492},
      doi = {http://dx.doi.org/10.1109/NANO.2011.6144584}
    }
    
    A.F. Kuloglu, B. Sarikavak-Lisesivdin, S.B. Lisesivdin & E. Ozbay First-principles calculations of Pd-terminated symmetrical armchair graphene nanoribbons 2013 Computational Materials Science
    Vol. 68(0), 18-22 
    DOI URL 
    Abstract: The effects of Palladium (Pd) termination on the electronic properties of armchair graphene nanoribbons (AGNRs) were calculated by using ab initio calculations. After a geometric optimization process, the electronic band structures, density of states, and binding energies of AGNRs with Na = 5-15 were calculated. Pd-termination was found to significantly influence the electronic properties of AGNRs. In DOS, many Q0D and Q1D type states were observed. Binding energy (BE) for single-side or both-side Pd-terminated structures represents characteristic drops with the increasing GNR width. With the increasing GNR width, the BEs of these structures become similar to hydrogenated structures. Because of the GNR width, dependent BE also gave information on the possible stiffness information, in which all of this information can be used in studies where controlled binding to graphene is required.
    Keywords: ATK; Application; Palladium; termination; passivation; graphene; GNR; nanoribbon; electronic properties; ab initio; adsorption; density of states; films
    Area: graphene
    BibTeX:
    @article{Kuloglu2013,
      author = {Kuloglu, A.F. and Sarikavak-Lisesivdin, B. and Lisesivdin, S.B. and Ozbay, E.},
      title = {First-principles calculations of Pd-terminated symmetrical armchair graphene nanoribbons},
      journal = {Computational Materials Science},
      year = {2013},
      volume = {68},
      number = {0},
      pages = {18--22},
      url = {http://www.sciencedirect.com/science/article/pii/S0927025612006003},
      doi = {http://dx.doi.org/10.1016/j.commatsci.2012.10.011}
    }
    
    Ruge Quhe, Ruixiang Fei, Qihang Liu, Jiaxin Zheng, Hong Li, Chengyong Xu, Zeyuan Ni, Yangyang Wang, Dapeng Yu, Zhengxiang Gao & Jing Lu Tunable and sizable band gap in silicene by surface adsorption 2012 Sci. Rep.
    Vol. 2, 853 
    DOI  
    Abstract: Opening a sizable band gap without degrading its high carrier mobility is as vital for silicene as for graphene to its application as a high-performance field effect transistor (FET). Our density functional theory calculations predict that a band gap is opened in silicene by single-side adsorption of alkali atom as a result of sublattice or bond symmetry breaking. The band gap size is controllable by changing the adsorption coverage, with an impressive maximum band gap up to 0.50 V. The ab initio quantum transport simulation of a bottom-gated FET based on a sodium-covered silicene reveals a transport gap, which is consistent with the band gap, and the resulting on/off current ratio is up to 10^8. Therefore, a way is paved for silicene as the channel of a high-performance FET.
    Keywords: ATK; Application; silicene; field-effect transistor; FET;
    Area: hexflats
    BibTeX:
    @article{Quhe2012a,
      author = {Quhe, Ruge and Fei, Ruixiang and Liu, Qihang and Zheng, Jiaxin and Li, Hong and Xu, Chengyong and Ni, Zeyuan and Wang, Yangyang and Yu, Dapeng and Gao, Zhengxiang and Lu, Jing},
      title = {Tunable and sizable band gap in silicene by surface adsorption},
      journal = {Sci. Rep.},
      publisher = {Macmillan Publishers Limited. All rights reserved},
      year = {2012},
      volume = {2},
      pages = {853},
      doi = {http://dx.doi.org/10.1038/srep00853}
    }
    
    Sudhanshu Choudhary & S Qureshi Theoretical study on effect of radial and axial deformation on electron transport properties in a semiconducting Si-C nanotube 2012 Bulletin of Materials Science
    Vol. 35Bulletin of Materials Science, 713-718 
    DOI  
    Abstract: We investigate electron transport properties in a deformed (8, 0) silicon carbide nanotube by applying self consistent non-equilibrium Green's function formalism in combination with the density-functional theory to a two-probe molecular junction constructed from deformed nanotube. The results suggest significant reduction in threshold voltage in the case of both radially compressed and axially elongated (8, 0) SiCNTs, a large difference in current-voltage characteristics was observed. Analysis of frontier molecular orbitals (FMO) and transmission spectrum show bandgap reduction in deformed nanotubes. Deformation introduces electronic states near the Fermi level, enhancing the conduction properties of (8, 0) SiCNT. The FMOs and the orbitals corresponding to peaks in T(E) around Fermi level obviously has some major contributions from the deformed site. However, localization of the electronic state near the Fermi level is weak in (8, 0) SiCNT, possibly because of its large bandgap.
    Keywords: ATK; Application; nanotube; SiCNT; armchair-zigzag; defects; deformation
    Area: nanotubes
    BibTeX:
    @article{Choudhary2012,
      author = {Choudhary, Sudhanshu and Qureshi, S},
      title = {Theoretical study on effect of radial and axial deformation on electron transport properties in a semiconducting Si-C nanotube},
      booktitle = {Bulletin of Materials Science},
      journal = {Bulletin of Materials Science},
      publisher = {Springer-Verlag},
      year = {2012},
      volume = {35},
      pages = {713-718},
      doi = {http://dx.doi.org/10.1007/s12034-012-0370-y}
    }
    
    Qihang Liu, Linze Li, Yafei Li, Zhengxiang Gao, Zhongfang Chen & Jing Lu Tuning Electronic Structure of Bilayer MoS2 by Vertical Electric Field: A First-Principles Investigation 2012 J. Phys. Chem. C
    Vol. 116(40)The Journal of Physical Chemistry C, 21556-21562 
    DOI  
    Abstract: Interest in the two-dimensional MoS2 material is consistently increasing because of its many potential applications, in particular in the next-generation nanoelectronic devices. By means of density functional theory computations, we systematically examined the effect of vertical electric field on the electronic structure of MoS2 bilayer. The bandgaps of the bilayer MoS2 monotonically decrease with an increasing vertical electric field. The critical electric fields, at which the semiconductor-to-metal transition occurs, are predicted to be in the range of 1.0-1.5 V/Å depending on different stacked conformations. Ab initio quantum transport simulations of a dual-gated bilayer MoS2 channel clearly confirm that the vertical electric field continuously manipulates the transmission gap of bilayer MoS2.
    Keywords: ATK; Application; MoS2; electric field; field effect transistor; FET; graphene; thin-films; nanosheets; graphene
    Area: graphene, dichalcogenides
    BibTeX:
    @article{Liu2012,
      author = {Liu, Qihang and Li, Linze and Li, Yafei and Gao, Zhengxiang and Chen, Zhongfang and Lu, Jing},
      title = {Tuning Electronic Structure of Bilayer MoS2 by Vertical Electric Field: A First-Principles Investigation},
      booktitle = {The Journal of Physical Chemistry C},
      journal = {J. Phys. Chem. C},
      publisher = {American Chemical Society},
      year = {2012},
      volume = {116},
      number = {40},
      pages = {21556--21562},
      doi = {http://dx.doi.org/10.1021/jp307124d}
    }
    
    Zhiyong Wang, Hong Li, Zheng Liu, Zujin Shi, Jing Lu, Kazu Suenaga, Soon-Kil Joung, Toshiya Okazaki, Zhennan Gu, Jing Zhou, Zhengxiang Gao, Guangping Li, Stefano Sanvito, Enge Wang & Sumio Iijima Mixed Low-Dimensional Nanomaterial: 2D Ultranarrow MoS2 Inorganic Nanoribbons Encapsulated in Quasi-1D Carbon Nanotubes 2010 J. Am. Chem. Soc.
    Vol. 132(39)Journal of the American Chemical Society, 13840-13847 
    DOI  
    Abstract: Quasi-one-dimensional nanotubes and two-dimensional nanoribbons are two fundamental forms of nanostructures, and integrating them into a novel mixed low-dimensional nanomaterial is fascinating and challenging. We have synthesized a stable mixed low-dimensional nanomaterial consisting of MoS2 inorganic nanoribbons encapsulated in carbon nanotubes (which we call nanoburritos). This route can be extended to the synthesis of nanoburritos composed of other ultranarrow transition-metal chalcogenide nanoribbons and carbon nanotubes. The widths of previously synthesized MoS2 ribbons are greater than 50 nm, while the encapsulated MoS2 nanoribbons have uniform widths down to 1-4 nm and layer numbers down to 1-3, depending on the nanotube diameter. The edges of the MoS2 nanoribbons have been identified as zigzag-shaped using both high-resolution transmission electron microscopy and density functional theory calculations.
    Keywords: ATK; Application; MoS2; nanotube; experimental comparison; nanoburritos; nitrogenase FeMo-cofactor; graphene nanoribbons; electronic structure; electrochemical/chemical synthesis; magnetic properties; stability; nanoparticles; nanoclusters; transition
    Area: graphene; nanotubes; dichalcogenides
    BibTeX:
    @article{Wang2010e,
      author = {Wang, Zhiyong and Li, Hong and Liu, Zheng and Shi, Zujin and Lu, Jing and Suenaga, Kazu and Joung, Soon-Kil and Okazaki, Toshiya and Gu, Zhennan and Zhou, Jing and Gao, Zhengxiang and Li, Guangping and Sanvito, Stefano and Wang, Enge and Iijima, Sumio},
      title = {Mixed Low-Dimensional Nanomaterial: 2D Ultranarrow MoS2 Inorganic Nanoribbons Encapsulated in Quasi-1D Carbon Nanotubes},
      booktitle = {Journal of the American Chemical Society},
      journal = {J. Am. Chem. Soc.},
      publisher = {American Chemical Society},
      year = {2010},
      volume = {132},
      number = {39},
      pages = {13840--13847},
      doi = {http://dx.doi.org/10.1021/ja1058026}
    }
    
    Zhi-Qiang Fan, Zhen-Hua Zhang, Ming Qiu, Xiao-Qing Deng & Gui-Ping Tang The site effects of B or N doping on I-V characteristics of a single pyrene molecular device 2012 Appl. Phys. Lett.
    Vol. 101(7), 073104-5 
    DOI  
    Abstract: Using the non-equilibrium Green's function method combined with the density functional theory, the electronic transport properties of boron (B) or nitrogen (N) doped pyrene molecular devices are investigated. The results show that effects of B or N doping on I-V characteristics of a single pyrene molecular device are not constant and can be changed by varying doped sites. More importantly, significant negative differential resistance (NDR) behaviors are found in B-doped pyrene molecular devices. The peak-to-valley ratio which is a typical character of NDR behavior is also sensitive to the B doped site.
    Keywords: ATK; Application; boron; density functional theory; doping; Green's function methods; molecular electronics; nitrogen
    Area: molecular electronics
    BibTeX:
    @article{Fan2012b,
      author = {Fan, Zhi-Qiang and Zhang, Zhen-Hua and Qiu, Ming and Deng, Xiao-Qing and Tang, Gui-Ping},
      title = {The site effects of B or N doping on I-V characteristics of a single pyrene molecular device},
      journal = {Appl. Phys. Lett.},
      publisher = {AIP},
      year = {2012},
      volume = {101},
      number = {7},
      pages = {073104--5},
      doi = {http://dx.doi.org/10.1063/1.4745842}
    }
    
    Vihar P. Georgiev, W.M.C. Sameera & John E. McGrady Attenuation of Conductance in Cobalt Extended Metal Atom Chains 2012 J. Phys. Chem. C
    Vol. 116(38)The Journal of Physical Chemistry C, 20163-20172 
    DOI  
    Abstract: Density functional theory, in conjunction with nonequilibrium Green?s functions, is used to explore the attenuation of the resistance of Cox wires along the series Co3(dpa)4(NCS)2, Co5(tpda)4(NCS)2, and Co7(teptra)4(NCS)2. At very low bias (0 < V < 25 mV) the conductance, G, decreases in the order G(Co3) > G(Co5) > G(Co7), consistent with experiment and with an anticipated inverse relationship between conductance and chain length. At higher voltages, however, the current-voltage responses of all three are striking nonlinear, and above 50 mV G(Co5) > G(Co3) > G(Co7). The very different behavior of the members of this homologous series can be traced to the different symmetries and multiplicities of their respective ground states, which in turn control the properties of the dominant transport channels.
    Keywords: ATK; Application; molecular electronics; bond-stretch isomerism; linear tricobalt compounds; string complexes; electron-transport; magnetic properties; tripyridyldiamido dianion; molecular junctions; crystal-structures; charge-transport; ab-initio; spin
    Area: molecular electronics; spin
    BibTeX:
    @article{Georgiev2012,
      author = {Georgiev, Vihar P. and Sameera, W. M. C. and McGrady, John E.},
      title = {Attenuation of Conductance in Cobalt Extended Metal Atom Chains},
      booktitle = {The Journal of Physical Chemistry C},
      journal = {J. Phys. Chem. C},
      publisher = {American Chemical Society},
      year = {2012},
      volume = {116},
      number = {38},
      pages = {20163--20172},
      doi = {http://dx.doi.org/10.1021/jp304807w}
    }
    
    Xiao-Fei Li, Ling-Ling Wang, Ke-Qiu Chen & Yi Luo Strong current polarization and negative differential resistance in chiral graphene nanoribbons with reconstructed (2,1)-edges 2012 Appl. Phys. Lett.
    Vol. 101(7), 073101-5 
    DOI  
    Abstract: We investigate electronic structures and transport properties of chiral-graphene-nanoribbons (CGNRs) with reconstructed (2,1)-edges. First principles results reveal that the (2,1)-CGNRs can be either spin non-polarized or polarized, depending on whether the edges are H-saturated or unsaturated. H-saturated systems are semiconductors with width-dependent transmission gap, while unsaturated systems are metallic at non-polarized state or at antiferromagnetic state and they are semiconductors at ferromagnetic state. Moreover, unsaturated systems possess strong current polarizations (nearly 100%) and a striking negative differential resistance behavior (with a peak-to-valley ratio about 10^5). These remarkable properties suggest the potential application of (2,1)-CGNRs in molectronics and spintronics.
    Keywords: ATK; Application; ab initio calculations; antiferromagnetic materials; electrical resistivity; ferromagnetic materials; graphene; magnetic semiconductors; nanomagnetics; nanoribbons; negative resistance; spin polarised transport; spin
    Area: graphene; spin
    BibTeX:
    @article{Li2012m,
      author = {Li, Xiao-Fei and Wang, Ling-Ling and Chen, Ke-Qiu and Luo, Yi},
      title = {Strong current polarization and negative differential resistance in chiral graphene nanoribbons with reconstructed (2,1)-edges},
      journal = {Appl. Phys. Lett.},
      publisher = {AIP},
      year = {2012},
      volume = {101},
      number = {7},
      pages = {073101--5},
      doi = {http://dx.doi.org/10.1063/1.4745506}
    }
    
    Kazunari Yoshizawa An Orbital Rule for Electron Transport in Molecules 2012 Acc. Chem. Res.
    Vol. 45(9)Accounts of Chemical Research, 1612-1621 
    DOI  
    Abstract: The transfer of electrons in molecules and solids is an essential process both in biological systems and in electronic devices. Devices that take advantage of the unique electronic properties of a single molecule have attracted much attention, and applications of these devices include molecular wire, molecular memory, and molecular diodes. The so-called Landauer formula with Green's function techniques provides a basis for theoretical calculations of coherent electron transport in metal-molecule-metal junctions. We have developed a chemical way of thinking about electron transport in molecules in terms of frontier orbital theory. The phase and amplitude of the HOMO and LUMO of pi-conjugated molecules determine the essential properties of their electron transport. By considering a close relationship between Green's function and the molecular orbital, we derived an orbital rule that would help our chemical understanding of the phenomenon. First, the sign of the product of the orbital coefficients at sites r and s in the HOMO should be different from the sign of the product of the orbital coefficients at sites r and s in the LUMO. Second, sites r and s in which the amplitude of the HOMO and LUMO is large should be connected. The derived rule allows us to predict essential electron transport properties, which significantly depend on the route of connection between a molecule and electrodes. Qualitative analyses of the site-dependent electron transport in naphthalene (as shown in the graphics) demonstrate that connections 1-4, 1-5, 2-3, and 2-6 are symmetry-allowed for electron transmission, while connections 1-8 and 2-7 are symmetry-forbidden. On the basis of orbital interaction analysis, we have extended this rule to metal-molecule-metal junctions of dithiol derivatives in which two gold electrodes have direct contacts with a molecule through two Au-S bonds. Recently we confirmed these theoretical predictions experimentally by using nanofabricated mechanically controllable break junctions to measure the single-molecule conductance of naphthalene dithiol derivatives. The measurement of the symmetry-allowed 1,4-naphthalene dithiol shows a single-molecule conductance that exceeds that of the symmetry-forbidden 2,7-naphthalene dithiol by 2 orders of magnitude. Because the HOMO and LUMO levels and the HOMO-LUMO gaps are similar in the derivatives, the difference in the measured molecular conductances arises from the difference in the phase relationship of the frontier orbitals. Thus, the phase, amplitude, and spatial distribution of the frontier orbitals provide a way to rationally control electron transport properties within and between molecules.
    Keywords: ATK; Application; review; molecular electronics; nanosized graphite sheets; current-voltage characteristics; quantum transport; organic-molecules; aromatic-hydrocarbons; tunneling current; single-molecule; charge-transfer; ground-state; conductance
    Area: molecular electronics
    BibTeX:
    @article{Yoshizawa2012,
      author = {Yoshizawa, Kazunari},
      title = {An Orbital Rule for Electron Transport in Molecules},
      booktitle = {Accounts of Chemical Research},
      journal = {Acc. Chem. Res.},
      publisher = {American Chemical Society},
      year = {2012},
      volume = {45},
      number = {9},
      pages = {1612--1621},
      doi = {http://dx.doi.org/10.1021/ar300075f}
    }
    
    Hong Li, Lu Wang, Qihang Liu, Jiaxin Zheng, Wai-Ning Mei, Zhengxiang Gao, Junjie Shi & Jing Lu High performance silicene nanoribbon field effect transistors with current saturation 2012 The European Physical Journal B - Condensed Matter and Complex Systems
    Vol. 85(8), 1-6 
    DOI  
    Abstract: We investigate field effect transistors (FETs) based on semiconducting armchair-edged silicene nanoribbons (ASiNRs) by using ab initio quantum transport calculations. These FETs have high performance with an I on/I off ratio of over 10^6 and a subthreshold swing as small as 90 mV/decade. Impressively, the output characteristic shows a saturation behavior. The drain-current saturation is an advantage with respect to device speed, but it's usually absent in carbon-based (e.g., graphene, graphene nanoribbons, carbon nanotubes, and organic single-molecule) FETs.
    Keywords: ATK; Application; silicene nanoribbon; field-effect transistor; FET; walled carbon nanotubes; nanowire transistors; transistors; transport-properties; epitaxial-graphene; ab-initio; length
    Area: hexflats
    BibTeX:
    @article{Li2012l,
      author = {Li, Hong and Wang, Lu and Liu, Qihang and Zheng, Jiaxin and Mei, Wai-Ning and Gao, Zhengxiang and Shi, Junjie and Lu, Jing},
      title = {High performance silicene nanoribbon field effect transistors with current saturation},
      journal = {The European Physical Journal B - Condensed Matter and Complex Systems},
      publisher = {Springer Berlin / Heidelberg},
      year = {2012},
      volume = {85},
      number = {8},
      pages = {1--6},
      doi = {http://dx.doi.org/10.1140/epjb/e2012-30220-2}
    }
    
    Zhi Yang, Shaoding Liu, Xuguang Liu, Yongzhen Yang, Xiuyan Li, Shijie Xiong & Bingshe Xu The magnetic and quantum transport properties of benzene-vanadium-borazine mixed sandwich clusters: a new kind of spin filter 2012 Journal of Physics: Condensed Matter
    Vol. 24(44), 445501- 
    DOI URL 
    Abstract: Using density functional theory and the non-equilibrium Green's function technique, we performed theoretical investigations on the magnetic and quantum transport properties of benzene-vanadium-borazine mixed organic/inorganic ligand sandwich clusters. The calculated results show that these finite sandwich clusters coupled to Ni electrodes exhibit novel quantum transport properties such as half-metallicity, negative differential resistance and spin-reversal effect, and can be viewed as a new kind of spin filter. However, for the infinite molecular wire, the ground state was identified as a ferromagnetic semiconductor with high stability. These findings suggest that the mixed organic/inorganic ligand sandwich clusters and molecular wires are promising materials for application in molecular electronics and spintronics.
    Keywords: ATK; Application; molecular electronics; spin filter; boron-nitride; magnetism; molecular wire; negative differential resistance; NDR; molecular electronic devices; ab-initio; decker sandwich; charge-transfer; complexes; ligand; wires; ferromagnetism; ferrocene; binding
    Area: molecular electronics; spin
    BibTeX:
    @article{Yang2012b,
      author = {Yang, Zhi and Liu, Shaoding and Liu, Xuguang and Yang, Yongzhen and Li, Xiuyan and Xiong, Shijie and Xu, Bingshe},
      title = {The magnetic and quantum transport properties of benzene-vanadium-borazine mixed sandwich clusters: a new kind of spin filter},
      journal = {Journal of Physics: Condensed Matter},
      year = {2012},
      volume = {24},
      number = {44},
      pages = {445501--},
      url = {http://stacks.iop.org/0953-8984/24/i=44/a=445501},
      doi = {http://dx.doi.org/10.1088/0953-8984/24/44/445501}
    }
    
    Manisha Aggarwal, Ashok Kumar & Inderpreet Kaur Computational Study on the Electronic Properties of Functionalized Graphene Nanoribbon 2012 International Journal for Science and Emerging Technologies with Latest Trends
    Vol. 4(1), 7-12 
    URL 
    Abstract: Graphene, the starting material for all the carbon nanostructures, has attracted the attention of all the researchers worldwide due to its remarkable electronic and transport properties like quantum Hall effect at room temperature, an ambipolar electric field effect along with ballistic conduction of charge carriers, tunable band gap and high elasticity. Graphene is a flat monolayer 2D system of carbon atoms organized into a honeycomb lattice with sp2 hybridization. Graphene is a zero band gap material which is the defining concept for semiconductor materials and essential for controlling the conductivity by electronic means. However bilayer graphene shows band gap of 0.25 eV when a vertical electric field is applied. A large number of methods have been employed to calculate graphene's properties; one of them is theoretical study using density functional theory (DFT) method. Here in this article we are calculating band structure, density of states and transmission spectrum using density functional theory calculations by varying the length and the width of graphene nanoribbon (GNR). Functionalization studies of GNR have also been conducted using ATK-DFT.
    Keywords: ATK; Application; graphene; density functional theory; band structure; functionalization
    Area: graphene
    BibTeX:
    @article{Aggarwal2012,
      author = {Manisha Aggarwal and Ashok Kumar and Inderpreet Kaur},
      title = {Computational Study on the Electronic Properties of Functionalized Graphene Nanoribbon},
      journal = {International Journal for Science and Emerging Technologies with Latest Trends},
      year = {2012},
      volume = {4},
      number = {1},
      pages = {7-12},
      url = {http://www.ijsett.com/images/Paper(4)7-12.pdf}
    }
    
    Anirban Basak, S K Manhas, Gaurav Kapil, Sudeb Dasgupta & Neeraj Jain A Simulation Study of the Effect of Platinum Contact on CNT Based Gas Sensors Using Self-Consistent Field with NEGF Method 2012 SISPAD, 169-172   
    Abstract: The electronic structure of the pi electrons of the CNT is highly affected by the presence of foreign molecules. This property can be utilized in CNT based gas sensing applications. In this work, we study bare zigzag CNT, NO2 adsorbed zigzag CNT, and Pt contacted NO2 adsorbed zigzag CNT to find the effectiveness of zigzag CNT and Pt in making a NO2 gas sensor. We find that bare zigzag CNT is a good material for NO2 detection and platinum make Schottky contact with zigzag CNT which can be used for gas sensing applications.
    Keywords: ATK; Application; nanotube; sensor
    Area: nanotubes
    BibTeX:
    @inproceedings{Basak2012,
      author = {Anirban Basak and S K Manhas and Gaurav Kapil and Sudeb Dasgupta and Neeraj Jain},
      title = {A Simulation Study of the Effect of Platinum Contact on CNT Based Gas Sensors Using Self-Consistent Field with NEGF Method},
      booktitle = {SISPAD},
      year = {2012},
      pages = {169-172}
    }
    
    S. Caliskan & M. Canturk Spin dependent transport behavior in small world networks 2012 The European Physical Journal B - Condensed Matter and Complex Systems
    Vol. 85(9), 1-8 
    DOI  
    Abstract: Density functional theory (DFT) combined with the non equilibrium Green's function formalism (NEGF) is applied to perform spin polarized transport calculations on small world network (SWN) systems consisting of atomic wires. Including the spin property in SWN structures leads to interesting electrical properties. It is revealed that the emerging spin polarization depends mainly on the SWN geometry given by the asymmetric distribution of loops joining the arbitrary atoms on the main chain. The spin-asymmetric behavior which yields the spin polarization is found to be largely determined by those loops which are close to the electrodes. However, spin polarization may vanish for a specific SWN structure due to symmetry.
    Keywords: ATK; Application; carbon atomic wire; atomic chain; spintronics; spin; generalized gradient approximation; quantized conductance; coherent transport; complex networks; quantum wires; point-contact; nanowires; semiconductors; nanomaterials; transmission
    Area: molecular electronics; spin
    BibTeX:
    @article{Caliskan2012,
      author = {Caliskan, S. and Canturk, M.},
      title = {Spin dependent transport behavior in small world networks},
      journal = {The European Physical Journal B - Condensed Matter and Complex Systems},
      publisher = {Springer Berlin / Heidelberg},
      year = {2012},
      volume = {85},
      number = {9},
      pages = {1--8},
      doi = {http://dx.doi.org/10.1140/epjb/e2012-30253-5}
    }
    
    Jikun Ding, Qiming Shao, Jinyu Zhang & Zhiping Yu Comparison for Various Kinds of Hamiltonian in Graphene Nanoribbon Quantum Transport Calculation 2012 SISPAD, 352-355   
    Abstract: The band structure and transport of an armchair and the zigzag graphene nanoribbon (GNR) are calculated using different types of Hamiltonians, including density functional-based tight binding (DFTB), extended Hückel theory (EHT), tight binding (TB), and density functional theory (DFT). Only the pz orbit is used for the carbon atom in the TB Hamiltonian (pz-TB). The other four orbits are used for the carbon atoms in the DFTB and EHT Hamiltonians. The transport calculation is performed using non-equilibrium Green's function (NEGF). The results show that all Hamiltonians have consistent band structures and I-V characteristics. Although pz-TB has low accuracy in describing the defects on GNR, it can still provide qualitatively correct band structures and I-V curves.
    Keywords: ATK; ATK-SE; Application; graphene nanoribbon; DFTB; Hückel; EHT; DFT; NEGF; defects
    Area: graphene
    BibTeX:
    @inproceedings{Ding2012,
      author = {Jikun Ding and Qiming Shao and Jinyu Zhang and and Zhiping Yu},
      title = {Comparison for Various Kinds of Hamiltonian in Graphene Nanoribbon Quantum Transport Calculation},
      booktitle = {SISPAD},
      year = {2012},
      pages = {352-355}
    }
    
    J.C. Dong & H. Li Monoatomic Layer Electronics Constructed by Graphene and Boron Nitride Nanoribbons 2012 J. Phys. Chem. C
    Vol. 116(32)The Journal of Physical Chemistry C, 17259-17267 
    DOI  
    Abstract: A new and simple kind of heterostructure nanoelectronics, which are free of metal electrodes, is constructed by a boron nitride nanoribbon (BNNR) seamlessly connected between two pieces of graphene nanoribbons (GNRs). The electron transport properties of devices based on such GNR-BNNR-GNR heterostructures are systematically investigated. The effects of vacancy, chirality, width, and boundary of nanoribbons on the electron transport properties of these devices are discussed. Energy gaps over 1 eV are observed in the electron transmission spectra of devices composed of these heterojunctions, indicating their pronounced field effect transistor (FET) characters. Removing hydrogen atoms at the boron edge of zigzag BNNR can result in 100% electron spin polarization in the GNR-BNNR-GNR FET. This study has implications for developing high-performance monatomic layer nanoelectronics with simple heterojunctions.
    Keywords: ATK; Application; graphene heterojunction; nanoribbon; boron-nitride; field effect transistor; FET; scale epitaxial graphene; bilayer graphene; transport
    Area: graphene
    BibTeX:
    @article{Dong2012a,
      author = {Dong, J. C. and Li, H.},
      title = {Monoatomic Layer Electronics Constructed by Graphene and Boron Nitride Nanoribbons},
      booktitle = {The Journal of Physical Chemistry C},
      journal = {J. Phys. Chem. C},
      publisher = {American Chemical Society},
      year = {2012},
      volume = {116},
      number = {32},
      pages = {17259--17267},
      doi = {http://dx.doi.org/10.1021/jp304189w}
    }
    
    Pradyumna Goli Current-Voltage Characteristics of Graphene Nanoribbons in the Ballistic Transport Regime 2012 Journal of Nanoelectronics and Optoelectronics
    Vol. 7(4), 381-385 
    DOI  
    Abstract: Extraordinary properties of graphene such as its extremely high room-temperature electron mobility and thermal conductivity make this material appealing for many electronic and sensor applications. The absence of the energy band-gap in graphene's electronic spectrum motivates investigation of graphene nano-ribbons in which the electronic "transport gap" regime can be achieved when the width of the nano-ribbons is sufficiently small. The exact physical origin of the "transport gap" and its dependence on the width and the shape of graphene edges are still the subjects of debates. Here we report the calculations of the electron transport in graphene nano-ribbons. The method used for this study is based on the non-equilibrium Greens function method and the density functional theory. We focus our analysis on the possibility to open the band gap, induce the gap states via defects and on controlling the electrical conductivity by the chemical and physical means. Specifically, we varied the width of the hydrogen saturated zigzag graphene nano-ribbon and studied its effect on the current-voltage characteristics. It has been observed that the width of the ribbons affects the current-voltage characteristics considerably. The transport properties of graphene nanoribbon such as Seebeck coefficient, Hall coefficient have been extracted from our calculations. Our results also show that the graphene zigzag nano-ribbons exhibit nonlinear behavior of the current-voltage characteristics owing to the overlapping of pi and pi* bands near the Fermi level. The obtained results are important for the proposed electronic and optoelectronic applications of graphene nano-ribbons.
    Keywords: graphene; graphene nanoribbon; density functional theory; ATK; Application; Seebeck coefficient; Hall coefficient;
    Area: graphene
    BibTeX:
    @article{Goli2012,
      author = {Goli, Pradyumna},
      title = {Current-Voltage Characteristics of Graphene Nanoribbons in the Ballistic Transport Regime},
      journal = {Journal of Nanoelectronics and Optoelectronics},
      year = {2012},
      volume = {7},
      number = {4},
      pages = {381--385},
      doi = {http://dx.doi.org/10.1166/jno.2012.1315}
    }
    
    Jason T. Haraldsen, Peter Wölfle & Alexander V. Balatsky Understanding the electric-field enhancement of the superconducting transition temperature for complex oxide interfaces 2012 Phys. Rev. B
    Vol. 85(13), 134501- 
    DOI  
    Abstract: We examine the enhancement of the interfacial superconductivity between LaAlO3 and SrTiO3 by an effective electric field. Through the breaking of inversion symmetry at the interface, we show that a term in the free energy, coupling the superfluid density and an electric field, can augment the superconductivity transition temperature. Microscopically, we show that an electric field can also produce changes in the carrier density by relating the measured capacitance to the density of states. Through the standard BCS (Bardeen, Cooper, and Schrieffer) weak-coupling interaction in bulk SrTiO3, we estimate the transition temperature.
    Keywords: ATK; Application; superconductivity; interfaces;
    Area: interfaces
    BibTeX:
    @article{Haraldsen2012,
      author = {Haraldsen, Jason T. and Wölfle, Peter and Balatsky, Alexander V.},
      title = {Understanding the electric-field enhancement of the superconducting transition temperature for complex oxide interfaces},
      journal = {Phys. Rev. B},
      publisher = {American Physical Society},
      year = {2012},
      volume = {85},
      number = {13},
      pages = {134501--},
      doi = {http://dx.doi.org/10.1103/PhysRevB.85.134501}
    }
    
    Ren Hua, Liang Wei, Zhao Peng & Liu De-Sheng Low Bias Negative Differential Resistance with Large Peak-to-Valley Ratio in a BDC60 Junction 2012 Chinese Physics Letters
    Vol. 29(7), 077301- 
    DOI URL 
    Abstract: Based on nonequilibrium Green's function method and density functional theory calculations, we investigate theoretically the electronic transport properties of 1,4-bis(fullero[c]pyrrolidinl-yï)benzene (BDC60). A low bias negative differential resistance with the peak-to-valley ratio as high as 305.41 is obtained. The observed negative differential resistance is explained in terms of the evolution of the transmission spectra, molecular projected self-consistent Hamiltonian states and molecular projected energy levels with applied bias.
    Keywords: ATK; Application; molecular electronics; fullerenes; transport-properties; carbon; conductance
    Area: molecular electronics; fullerenes
    BibTeX:
    @article{Hua2012,
      author = {Hua, Ren and Wei, Liang and Peng, Zhao and De-Sheng, Liu},
      title = {Low Bias Negative Differential Resistance with Large Peak-to-Valley Ratio in a BDC60 Junction},
      journal = {Chinese Physics Letters},
      year = {2012},
      volume = {29},
      number = {7},
      pages = {077301--},
      url = {http://stacks.iop.org/0256-307X/29/i=7/a=077301},
      doi = {http://dx.doi.org/10.1088/0256-307X/29/7/077301}
    }
    
    Neeraj K. Jaiswal, Pankaj Srivastava & A.S. Sengar Enhancing metallicity in zigzag graphene nanoribbons with adsorbed/substitutionally doped copper atoms 2012 Nanotechnology (IEEE-NANO), 2012 12th IEEE Conference on, 1-4  DOI  
    Abstract: Width dependent properties of Cu doped zigzag graphene nanoribbons (ZGNR) have been examined with density functional theory. We considered Cu as an adsorbed atom as well as a substitutional dopant (SD) at edge and the centre of ZGNR. It is revealed that adsorption and SD affect the stability of the ribbons in a different manner. Adsorption is energetically favorable whereas SD results in stronger binding of Cu atom with ZGNR. Edge is found as the preferred site for both types of Cu doping. The electronic property of ZGNR is effectively modified by the presence of Cu atoms and enhanced metallicity is observed in nanoribbons with substitutional Cu impurity. The observed high metallicity of Cu doped ZGNR is crucial particularly for the nanoelectronic interconnects.
    Keywords: ATK; Application; graphene; doping; interconnections; formation energy; binding energy; transmission spectra
    Area: graphene
    BibTeX:
    @inproceedings{Jaiswal2012b,
      author = {Jaiswal, Neeraj K. and Srivastava, Pankaj and Sengar, A. S.},
      title = {Enhancing metallicity in zigzag graphene nanoribbons with adsorbed/substitutionally doped copper atoms},
      booktitle = {Nanotechnology (IEEE-NANO), 2012 12th IEEE Conference on},
      year = {2012},
      pages = {1--4},
      doi = {http://dx.doi.org/10.1109/NANO.2012.6321984}
    }
    
    Satoshi Kaneko, Lu Wang, Guangfu Luo, Jing Lu, Shigeru Nagase, Satoru Sato, Michio Yamada, Zdenek Slanina, Takeshi Akasaka & Manabu Kiguchi Electron transport through single endohedral Ce@C_82 metallofullerenes 2012 Phys. Rev. B
    Vol. 86(15), 155406- 
    DOI  
    Abstract: The electron transport through a single endohedral Ce@C82 metallofullerene bridging between metal electrodes was investigated with experimental (break junction) as well as theoretical (density functional theory coupled with the nonequilibrium Green's function formalism) techniques. The single Ce@C82 molecule junction showing a high and fixed conductance value was fabricated by direct binding of the metallofullerene to Ag electrodes. The junction had a conductance of 0.28(±0.05)G0 (G0 = 2e2/h), which was much larger than that of single molecule junctions having anchoring groups (<0.01G0), but only half that of the single C60 molecule junction of 0.5G0. The unexpected reduced conductance of the single Ce@C82 molecule junction compared with that of the single C60 molecule junction was supported by the ab initio quantum transport calculations and was explained in terms of the localization of electrons in the C82 cage. In the case of the Au electrodes, the single Ce@C82 molecule junction was not formed by the break junction technique because the Ce@C82 molecule could not be trapped in the large Au nanogap, which was formed just after breaking the Au contacts.
    Keywords: ATK; Application; molecular electronics; fullerenes; molecular electronics; anchoring groups; conductance; density; chemistry; junctions; exchange; behavior
    Area: molecular electronics; fullerenes
    BibTeX:
    @article{Kaneko2012,
      author = {Kaneko, Satoshi and Wang, Lu and Luo, Guangfu and Lu, Jing and Nagase, Shigeru and Sato, Satoru and Yamada, Michio and Slanina, Zdenek and Akasaka, Takeshi and Kiguchi, Manabu},
      title = {Electron transport through single endohedral Ce@C_82 metallofullerenes},
      journal = {Phys. Rev. B},
      publisher = {American Physical Society},
      year = {2012},
      volume = {86},
      number = {15},
      pages = {155406--},
      doi = {http://dx.doi.org/10.1103/PhysRevB.86.155406}
    }
    
    Hong Seok Kang Spin-polarized transport through heterobilayers of graphene nanoribbons and ruthenium-porphyrin tapes 2012 Chemical Physics
    Vol. 405(0), 148-154 
    DOI  
    Abstract: Using the first-principles calculation, we have shown that armchair graphene nanoribbons (aGNR) exhibit highly spin-polarized transport by forming heterobilayers with one-dimensional ruthenium porphyrin tapes (Ru-PPTs). Due to stronger electronic coupling, the bilayer formation between aGNRs and doubly-linked (DL) Ru-PPTs is stronger than that between aGNRs and triply-linked (TL) Ru-PPTs. While the TL bilayer is a quasi-metal, the DL bilayer preserves the half-metallic character of the underlying DL Ru-PPT. At an applied bias of 0.1 V, the conductance of the DL heterobilayer is 99.7% spin-polarized.
    Keywords: first-principles calculation; armchair graphene nanoribbon; porphyrin tapes; heterobilayer; half-metal; conductance; ATK; Application
    Area: graphene
    BibTeX:
    @article{Kang2012,
      author = {Kang, Hong Seok},
      title = {Spin-polarized transport through heterobilayers of graphene nanoribbons and ruthenium-porphyrin tapes},
      journal = {Chemical Physics},
      year = {2012},
      volume = {405},
      number = {0},
      pages = {148--154},
      doi = {http://dx.doi.org/10.1016/j.chemphys.2012.07.001}
    }
    
    Junya Koga, Yuta Tsuji & Kazunari Yoshizawa Orbital Control of Single-Molecule Conductance Perturbed by pi-Accepting Anchor Groups: Cyanide and Isocyanide 2012 J. Phys. Chem. C
    Vol. 116(38)The Journal of Physical Chemistry C, 20607-20616 
    DOI  
    Abstract: Electron transport properties through benzene molecules disubstituted with pi-accepting cyanide and isocyanide anchor groups at their para and meta positions are investigated on the basis of a qualitative orbital analysis at the Hückel molecular orbital level of theory. The applicability of a previously derived orbital symmetry rule for electron transport is extended to the systems perturbed by the pi-accepting anchor groups, where the HOMO-LUMO symmetry in the molecular orbital energies relative to the Fermi level is removed. The conservation of the HOMO-LUMO symmetry in the spatial distribution of the molecular orbitals between the unperturbed benzene molecule and the perturbed molecules with the anchor groups rationalizes symmetry-allowed electron transport through the para isomers. On the other hand, destructive interferences between the nearly 2-fold degenerate frontier orbitals constructed from the 2-fold degenerate orbitals of the unperturbed benzene molecule and the anchor groups lead to symmetry-forbidden electron transport through the meta isomers. The qualitative orbital thinking is supported by more quantitative density functional theory (DFT) calculations combined with the nonequilibrium Green's function (NEGF) method. The orbital analysis is a powerful tool for the understanding and rational design of molecular devices composed of pi-conjugated hydrocarbons and those perturbed by the pi-accepting anchor groups.
    Keywords: ATK; Application; molecular electronics; nanosized graphite sheets; electron transport; quantum transport; contact resistance; tunneling current; charge transport; metal junctions; terminal groups; density; views
    Area: molecular electronics
    BibTeX:
    @article{Koga2012,
      author = {Koga, Junya and Tsuji, Yuta and Yoshizawa, Kazunari},
      title = {Orbital Control of Single-Molecule Conductance Perturbed by pi-Accepting Anchor Groups: Cyanide and Isocyanide},
      booktitle = {The Journal of Physical Chemistry C},
      journal = {J. Phys. Chem. C},
      publisher = {American Chemical Society},
      year = {2012},
      volume = {116},
      number = {38},
      pages = {20607--20616},
      doi = {http://dx.doi.org/10.1021/jp3068156}
    }
    
    Xingxing Li, Xiaojun Wu, Zhenyu Li, Jinlong Yang & J.G. Hou Bipolar magnetic semiconductors: a new class of spintronics materials 2012 Nanoscale
    Vol. 4(18), 5680-5685 
    DOI  
    Abstract: Electrical control of spin polarization is very desirable in spintronics, since electric fields can be easily applied locally, in contrast to magnetic fields. Here, we propose a new concept of bipolar magnetic semiconductors (BMS) in which completely spin-polarized currents with reversible spin polarization can be created and controlled simply by applying a gate voltage. This is a result of the unique electronic structure of BMS, where the valence and conduction bands possess opposite spin polarization when approaching the Fermi level. BMS is thus expected to have potential for various applications. Our band structure and spin-polarized electronic transport calculations on semi-hydrogenated single-walled carbon nanotubes confirm the existence of BMS materials and demonstrate the electrical control of spin-polarization in them.
    Keywords: ATK; Application; molecular electronics; spin; magnetism; nanotube; electron-spin; carbon nanotubes; ferromagnetism; magnetoresistance; nanostructures; manipulation; transition; transport; exchange; fields
    Area: nanotubes; spin; semi
    BibTeX:
    @article{Li2012k,
      author = {Li, Xingxing and Wu, Xiaojun and Li, Zhenyu and Yang, Jinlong and Hou, J. G.},
      title = {Bipolar magnetic semiconductors: a new class of spintronics materials},
      journal = {Nanoscale},
      publisher = {The Royal Society of Chemistry},
      year = {2012},
      volume = {4},
      number = {18},
      pages = {5680--5685},
      doi = {http://dx.doi.org/10.1039/C2NR31743E}
    }
    
    Ahmed Mahmoud & Paolo Lugli Transport characterization of a gated molecular device with negative differential resistance 2012 Nanotechnology (IEEE-NANO), 2012 12th IEEE Conference on, 1-5  DOI  
    Abstract: Due to increasing demand for advances in minimization, power consumption and speed of electronic devices, new technologies are emerging in order to replace/support the current semiconductor technology. Molecular electronics is one of the promising technologies that can offer an extreme increase in the integration density, since single molecules could be employed as active electronic devices. This theoretical paper deals with the transport characteristics of a gated molecular device, employing dithiolated Oligo-Phenylene Vinylene (OPV) molecules as testbed. The output current curves show a gate voltage dependency. In addition, a negative differential resistance (NDR) is observed. Transmission spectra, charge density distributions and potential profiles of the molecular device are provided to explain of the gate dependency and NDR behavior.
    Keywords: ATK-SE; Application; molecular devices; negative differential; resistance; oligo-phenylene vinylene; NEGF; molecular electronics; negative differential resistance; NDR
    Area: molecular electronics
    BibTeX:
    @inproceedings{Mahmoud2012,
      author = {Mahmoud, Ahmed and Lugli, Paolo},
      title = {Transport characterization of a gated molecular device with negative differential resistance},
      booktitle = {Nanotechnology (IEEE-NANO), 2012 12th IEEE Conference on},
      year = {2012},
      pages = {1--5},
      doi = {http://dx.doi.org/10.1109/NANO.2012.6321941}
    }
    
    L. Pan, H.J. Liu, X.J. Tan, H.Y. Lv, J. Shi, X.F. Tang & G. Zheng Thermoelectric properties of armchair and zigzag silicene nanoribbons 2012 Phys. Chem. Chem. Phys.
    Vol. 14(39), 13588-13593 
    DOI  
    Abstract: Using the nonequilibrium Green's function method and nonequilibrium molecular dynamics simulations, we discuss the possibility of using silicene nanoribbons (SiNRs) as high performance thermoelectric materials. It is found that SiNRs are structurally stable if the edge atoms are passivated by hydrogen, and those with armchair edges usually exhibit much better thermoelectric performance than their zigzag counterparts. The room temperature ZT value of armchair SiNRs shows a width-dependent oscillating decay, while it decreases slowly with increasing ribbon width for the zigzag SiNRs. In addition, there is a strong temperature dependence of the thermoelectric performance of these SiNRs. Our theoretical calculations indicate that by optimizing the doping level and applied temperature, the ZT value of SiNRs could be enhanced to as high as 4.9 which suggests their very appealing thermoelectric applications.
    Keywords: ATK; Application; silicene nanoribbon; thermoelectric properties; ZT; Seebeck coefficient; ab initio molecular dynamics; nanowires; figure of merit; performance; simulation; nanotubes; systems; metals
    Area: hexflats; thermo
    BibTeX:
    @article{Pan2012,
      author = {Pan, L. and Liu, H. J. and Tan, X. J. and Lv, H. Y. and Shi, J. and Tang, X. F. and Zheng, G.},
      title = {Thermoelectric properties of armchair and zigzag silicene nanoribbons},
      journal = {Phys. Chem. Chem. Phys.},
      publisher = {The Royal Society of Chemistry},
      year = {2012},
      volume = {14},
      number = {39},
      pages = {13588--13593},
      doi = {http://dx.doi.org/10.1039/C2CP42645E}
    }
    
    Sweta Parashar, Pankaj Srivastava & Manisha Pattanaik First-principles study of naphthalene-based single-electron transistor 2012 Applied Nanoscience
    Vol. 2(3), 385-388 
    DOI  
    Abstract: We have performed first-principle calculations based on density functional theory (DFT) and non-equilibrium greens functions (NEGF) for calculating the charging energies of molecular system weakly coupled to an environment. We apply this approach to the molecule naphthalene, which is lying flat on gate dielectric between the source and drain electrodes. Our calculated values of charging energy for naphthalene in an isolated case are in good agreement with experimental values. Further, in an electrostatic environment, the result shows renormalization of molecular energy levels and therefore reduces the charging energy of naphthalene. Subsequently, the charge stability diagram of naphthalene based single-electron transistor (SET) has been obtained by calculating the charging energies as a function of an external gate potential. This diagram shows the dependence of SET conductance on the gate voltage and the source-drain bias. Our implementation is intended to predict the charging energies of the naphthalene-based SETs that reveals further scope in realization of the devices at nanoscale.
    Keywords: single-electron transistor; charging energy; ionization energy; electron affinity; charge stability diagram; ATK; Application
    Area: SET
    BibTeX:
    @article{Parashar2012,
      author = {Parashar, Sweta and Srivastava, Pankaj and Pattanaik, Manisha},
      title = {First-principles study of naphthalene-based single-electron transistor},
      journal = {Applied Nanoscience},
      publisher = {Springer Berlin / Heidelberg},
      year = {2012},
      volume = {2},
      number = {3},
      pages = {385--388},
      doi = {http://dx.doi.org/10.1007/s13204-012-0112-x}
    }
    
    Lei Shen, Minggang Zeng, Suchun Li, Michael B. Sullivan & Yuan Ping Feng Electron transmission modes in electrically biased graphene nanoribbons and their effects on device performance 2012 Phys. Rev. B
    Vol. 86(11), 115419- 
    DOI  
    Abstract: Using ab initio transport methods, we investigate electron transmission modes (channels, pathways, and intensities) in electrically biased graphene nanoribbons (GNRs) under different growth conditions. In addition to the bond currents, we report loop currents in such devices, induced by the electrons hopping between carbon atoms of the same sublattice under bias. The loop current channel as well as the bond current channel play an important role in the local current in electrically biased GNR-based devices. The effect of edge functional groups and surface defects/groups on device performance depends on the current pathway and intensity in these two channels. Understanding the details of local currents in GNRs paves the way to make high-performance GNR-based electronic devices, such as GNR field effect transistors.
    Keywords: ATK; Application; graphene nanoribbon; field effect transistors; FET; carbon nanotubes; transistors; magnetoresistance; transport; defects; edges
    Area: graphene
    BibTeX:
    @article{Shen2012a,
      author = {Shen, Lei and Zeng, Minggang and Li, Suchun and Sullivan, Michael B. and Feng, Yuan Ping},
      title = {Electron transmission modes in electrically biased graphene nanoribbons and their effects on device performance},
      journal = {Phys. Rev. B},
      publisher = {American Physical Society},
      year = {2012},
      volume = {86},
      number = {11},
      pages = {115419--},
      doi = {http://dx.doi.org/10.1103/PhysRevB.86.115419}
    }
    
    Anurag Srivastava & Neha Tyagi Pressure-induced phase transition in Ga 1-x In x As: ab initio study 2012 High Pressure Research
    Vol. 32(2)High Pressure Research, 299-308 
    DOI  
    Abstract: The high pressure phase transitions in Ga 1-x In x As (x=0.25, 0.5 and 0.75) alloys have been investigated using the ab initio density functional theory approach. The total energies and ground state properties have been analyzed using both the local density as well as generalized gradient approximations as exchange-correlation functionals. The study computes the structural phase transition in Ga 1-x In x As from its most stable zinc-blende- (B3) type phase to hypothetical rocksalt- (B1) type phase in the pressure range of 3-14 GPa. The observed transition pressures for the host binary compounds are in close agreement with their experimental/theoretical counterparts. The effect of introduction of indium in GaAs has also been analyzed on the lattice parameter, bulk modulus and transition pressure.
    Keywords: ab initio; phase transition; high pressure; GaAs; InAs; III-V; alloys; ATK; Application
    Area: semi
    BibTeX:
    @article{Srivastava2012c,
      author = {Srivastava, Anurag and Tyagi, Neha},
      title = {Pressure-induced phase transition in Ga 1-x In x As: ab initio study},
      booktitle = {High Pressure Research},
      journal = {High Pressure Research},
      publisher = {Taylor & Francis},
      year = {2012},
      volume = {32},
      number = {2},
      pages = {299--308},
      doi = {http://dx.doi.org/10.1080/08957959.2012.686613}
    }
    
    Anurag Srivastava & Neha Tyagi Pressure-induced phase transition and electronic properties of AlN nanowires: an ab initio study 2012 Phase TransitionsPhase Transitions, 1-13  DOI URL 
    Abstract: The structural stability of AlN nanowires have been analyzed in wurtzite (B4), zincblende (B3), rocksalt (B1) and CsCl (B2) type phases using density functional theory based ab initio approach. The total energy calculations have been performed in a self-consistent manner using local density approximation as exchange correlation functional. The analysis finds the B4 type phase as most stable amongst the other phases taken into consideration and observes the structural phase transition from B4>B3, B4>B1, B4>B2, B3>B1 and B3>B2 at 42.7, 76.54, 142, 30.4 and 108.9 GPa respectively. Lattice parameter, bulk modulus and pressure derivatives of AlN nanowires have also been calculated for all the stable phases. The electronic band structure analysis of AlN nanowires shows a semiconducting nature in its B4, B3 and B1 type phases, whereas the B2 type phase is found to be metallic.
    Keywords: AlN; nanowires; phase transition; electronic properties; ab initio; ATK; Application
    Area: semi
    BibTeX:
    @article{Srivastava2012d,
      author = {Srivastava, Anurag and Tyagi, Neha},
      title = {Pressure-induced phase transition and electronic properties of AlN nanowires: an ab initio study},
      booktitle = {Phase Transitions},
      journal = {Phase Transitions},
      publisher = {Taylor & Francis},
      year = {2012},
      pages = {1--13},
      url = {http://www.tandfonline.com/doi/abs/10.1080/01411594.2012.693611},
      doi = {http://dx.doi.org/10.1080/01411594.2012.693611}
    }
    
    Anurag Srivastava, Arpit Jain, Rajnish Kurchania & Neha Tyagi Width Dependent Electronic Properties of Graphene Nanoribbons: An Ab-Initio Study 2012 Journal of Computational and Theoretical Nanoscience
    Vol. 9(7), 1008-1013 
    DOI  
    Abstract: We have analyzed the electronic properties of armchair and zigzag shaped graphene nanoribbons (GNRs) using density functional theory based ab-initio approach. The present computation employs the Perdew Zunger (PZ) type parameterized local density approximation (LDA) and revised Perdew Burke Ernzerhof (RPBE) type generalized gradient approximation (GGA) as exchange correlation functional. The calculated electronic band gap and density of states shows a close match with its other theoretical counterparts. In another observation, we have found a non linear variation of GNRs energy bandgap as a function of width.
    Keywords: ATK; Application; graphene nanoribbons; DFT; electronic properties; energy band gap; generalized gradient approximation; bilayer graphene; doped graphene; transparent; films
    Area: graphene
    BibTeX:
    @article{Srivastava2012e,
      author = {Srivastava, Anurag and Jain, Arpit and Kurchania, Rajnish and Tyagi, Neha},
      title = {Width Dependent Electronic Properties of Graphene Nanoribbons: An Ab-Initio Study},
      journal = {Journal of Computational and Theoretical Nanoscience},
      year = {2012},
      volume = {9},
      number = {7},
      pages = {1008--1013},
      doi = {http://dx.doi.org/10.1166/jctn.2012.2133}
    }
    
    Aleksandar Staykov, Xinqian Li, Yuta Tsuji & Kazunari Yoshizawa Current Rectification in Nitrogen- and Boron-Doped Nanographenes and Cyclophanes 2012 J. Phys. Chem. C
    Vol. 116(34)The Journal of Physical Chemistry C, 18451-18459 
    DOI  
    Abstract: Electron transport properties of boron- and nitrogen-doped polycyclic aromatic hydrocarbons and cyclophanes are investigated with the nonequilibrium Green's function method and compared to transport properties of the unsubstituted species. The aim of the study is to derive the effect of the heteroatomic defects on the conductance of nanographenes and to propose new effective ways for current control and design of carbon devices. Of special interest are the electrical current rectifying properties of asymmetrically doped nanographenes and cyclophanes, as well as the rectification mechanism. The mechanisms of donor-pi bridge-acceptor and donor-pi bridge-acceptor rectification are used to explain the diode-like properties of asymmetrically doped nanographenes and cyclophanes. The electron-rich nitrogen and electron-poor boron heteroatoms introduce conductance channels within the highest occupied molecular orbital/lowest unoccupied molecular orbital gaps of the hydrocarbons and cyclophanes and significantly enhance the conductance. The combination of nitrogen and boron impurities in one polycyclic aromatic hydrocarbon leads to asymmetrical I/V curves. The rectification is further enhanced in the cyclophanes where the boron impurities are located in one of the layers and the nitrogen impurities in the other. Owing to the efficient separation of the donor and acceptor parts, a higher rectification ratio is estimated. The rectifying properties of the asymmetrically doped carbon materials are derived from the nonequilibrium Green's function theory. The main reason for the rectification is found to be the interaction of the external electric field induced between the electrodes with the molecular orbitals of the asymmetrically doped hydrocarbons.
    Keywords: molecular electronics; ATK; Application; doping; nanographenes; rectification;
    Area: molecular electronics
    BibTeX:
    @article{Staykov2012,
      author = {Staykov, Aleksandar and Li, Xinqian and Tsuji, Yuta and Yoshizawa, Kazunari},
      title = {Current Rectification in Nitrogen- and Boron-Doped Nanographenes and Cyclophanes},
      booktitle = {The Journal of Physical Chemistry C},
      journal = {J. Phys. Chem. C},
      publisher = {American Chemical Society},
      year = {2012},
      volume = {116},
      number = {34},
      pages = {18451--18459},
      doi = {http://dx.doi.org/10.1021/jp303843k}
    }
    
    K. Tang, Z. Ni, Q. Liu, R. Quhe, Q. Zheng, J. Zheng, R. Fei, Z. Gao & J. Lu Electronic and transport properties of a biased multilayer hexagonal boron nitride 2012 The European Physical Journal B - Condensed Matter and Complex Systems
    Vol. 85(9), 301 
    DOI  
    Abstract: We explore the electronic and transport properties out of a biased multilayer hexagonal boron nitride (h-BN) by first-principles calculations. The band gaps of multilayer h-BN decrease almost linearly with increasing perpendicular electric field, irrespective of the layer number N and stacking manner. The critical electric filed ( E 0 ) required to close the band gap decreases with the increasing N and can be approximated by E 0 = 3.2/(N-1) (eV). We provide a quantum transport simulation of a dual-gated 4-layer h-BN with graphene electrodes. The transmission gap in this device can be effectively reduced by double gates, and a high on-off ratio of 3000 is obtained with relatively low voltage. This renders biased MLh-BN a promising channel in field effect transistor fabrication.
    Keywords: ATK; Application; graphane; field-effect transistor; FET; hexagonal boron-nitride; bilayer graphene; bandgap
    Area: graphene
    BibTeX:
    @article{Tang2012a,
      author = {Tang, K. and Ni, Z. and Liu, Q. and Quhe, R. and Zheng, Q. and Zheng, J. and Fei, R. and Gao, Z. and Lu, J.},
      title = {Electronic and transport properties of a biased multilayer hexagonal boron nitride},
      journal = {The European Physical Journal B - Condensed Matter and Complex Systems},
      publisher = {Springer Berlin / Heidelberg},
      year = {2012},
      volume = {85},
      number = {9},
      pages = {301},
      doi = {http://dx.doi.org/10.1140/epjb/e2012-30236-6}
    }
    
    Yangyang Wang, Jiaxin Zheng, Zeyuan Ni, Ruixiang Fei, Qihang Liu, Ruge Quhe, Chengyong Xu, Jing Zhou, Zhengxiang Gao & Jing Lu Half-metallic Silicene And Germanene Nanoribbons: Towards High-performance Spintronics Device 2012 NANO
    Vol. 7(5)Nano, 1250037- 
    DOI  
    Abstract: By using first-principles calculations, we predict that an in-plane homogenous electrical field can induce half-metallicity in hydrogen-terminated zigzag silicene and germanene nanoribbons (ZSiNRs and ZGeNRs). A dual-gated finite ZSiNR device reveals a nearly perfect spin-filter efficiency (SFE) of up to 99% while a quadruple-gated finite ZSiNR device serves as an effective spin field effect transistor (FET) with an on/off current ratio of over 100 from ab initio quantum transport simulation. This discovery opens up novel prospect of silicene and germanene in spintronics.
    Keywords: ATK; Application; silicene nanoribbon; germanene nanoribbon; half-metallicity; spin-filter; spin field effect transistor; first-principles calculation; graphene nanoribbons; spin transport; transistors; magnetoresistance; molecules
    Area: hexflats; spin
    BibTeX:
    @article{Wang2012b,
      author = {Wang, Yangyang and Zheng, Jiaxin and Ni, Zeyuan and Fei, Ruixiang and Liu, Qihang and Quhe, Ruge and Xu, Chengyong and Zhou, Jing and Gao, Zhengxiang and Lu, Jing},
      title = {Half-metallic Silicene And Germanene Nanoribbons: Towards High-performance Spintronics Device},
      booktitle = {Nano},
      journal = {NANO},
      publisher = {World Scientific Publishing Co.},
      year = {2012},
      volume = {7},
      number = {5},
      pages = {1250037--},
      doi = {http://dx.doi.org/10.1142/S1793292012500373}
    }
    
    X.Z. Wu, M.Q. Long, L.N. Chen, C. Cao, S.S. Ma & H. Xu The effects of side groups on the electronic transport properties of carbon chain molecular devices 2012 Physica E: Low-dimensional Systems and Nanostructures
    Vol. 45(0), 82-85 
    DOI  
    Abstract: Applying nonequilibrium Green's functions in combination with the density functional theory, we investigated the effect of amino and hydroxyl groups on the transport property of the carbon atomic chains. The results show the conductance oscillation with the length and the parity of the carbon atomic chains, and the electronic transport properties can be modulated by the sites of amino and hydroxyl groups. And also, the negative differential resistance behaviors can be observed clearly. These phenomena may originate from the interaction of side groups with the carbon atomic chains and the change in coupling degree between the molecular orbitals and electrode states.
    Keywords: ATK; Application; molecular electronics; atomic chain; conductance
    Area: molecular electronics
    BibTeX:
    @article{Wu2012b,
      author = {Wu, X.Z. and Long, M.Q. and Chen, L.N. and Cao, C. and Ma, S.S. and Xu, H.},
      title = {The effects of side groups on the electronic transport properties of carbon chain molecular devices},
      journal = {Physica E: Low-dimensional Systems and Nanostructures},
      year = {2012},
      volume = {45},
      number = {0},
      pages = {82--85},
      doi = {http://dx.doi.org/10.1016/j.physe.2012.07.011}
    }
    
    Ting-Ting Wu, Xue-Feng Wang, Yongjing Jiang & Liping Zhou Spin Transport in Be Edge-Doped Graphene Nanoribbon 2012 Journal of Nanoscience and Nanotechnology
    Vol. 12(8), 6467-6471 
    DOI  
    Abstract: We report an atomistic simulation of spin dependent charge transport in zigzag graphene nanoribbons with 4 zigzag chains doped by a Beryllium atom on one edge. The spin dependent density functional theory with norm-conserving atomic basis set is employed to describe the system and the current versus voltage behavior is calculated by the nonequilibrium Green's function method for quantum transport. The Be impurity atom suppresses the local magnetization near the edge and the transmitted charge current becomes spin polarized accordingly. Both spin-up and spin-down transmission spectra are modified significantly but in different ways. Distinguished from the previous doping results of other impurity elements, here we observe negative differential resistance for only one of the spins in the nonlinear transport regime below bias 1.5 V. Molecular projected Hamiltonian energy spectrum near the impurity shows that the impurity removes the energy degeneracy of spin in perfect ribbon. The current versus voltage shows semiconductor behavior with fluctuating spin polarization of amplitude up to 37%
    Keywords: ATK; Application; doping; spin transport; graphene nanoribbon; negative differential resistance; NDR; defects
    Area: graphene; spin
    BibTeX:
    @article{Wu2012c,
      author = {Wu, Ting-Ting and Wang, Xue-Feng and Jiang, Yongjing and Zhou, Liping},
      title = {Spin Transport in Be Edge-Doped Graphene Nanoribbon},
      journal = {Journal of Nanoscience and Nanotechnology},
      year = {2012},
      volume = {12},
      number = {8},
      pages = {6467--6471},
      doi = {http://dx.doi.org/10.1166/jnn.2012.5440}
    }
    
    Jian-Fei Yang, Liping Zhou, Qin Han & Xue-Feng Wang Bias-Controlled Giant Magnetoresistance through Cyclopentadienyl-Iron Multidecker Molecules 2012 J. Phys. Chem. C
    Vol. 116(37)The Journal of Physical Chemistry C, 19996-20001 
    DOI  
    Abstract: We investigated giant magnetoresistance (GMR) across cyclopentadienyl-iron multidecker molecules [Fe_m(C5H5)_n] using the density functional theory and nonequilibrium Green's function techniques. An oscillation behavior of the molecular magnetic moments was observed. Spin-polarized transport calculations through the lead-multidecker molecule-lead junctions predicted large bias-controlled magnetoresistive response, with the highest GMR ratio up to 2.0*10^4%. The positive to negative conversion of the GMR values was also observed with bias change. The transmission spectra and eigenvalues of the molecular junctions were calculated to understand the mechanism of spin transport in these systems. Various ways to manipulate the GMR behavior are illustrated, opening up prospects of new molecular spintronic devices.
    Keywords: ATK; Application; molecular electronics; giant magnetoresistance; sandwich clusters; spin transport; benzene; wires; ferromagnetism; spintronics; metals
    Area: molecular electronics; spin;
    BibTeX:
    @article{Yang2012,
      author = {Yang, Jian-Fei and Zhou, Liping and Han, Qin and Wang, Xue-Feng},
      title = {Bias-Controlled Giant Magnetoresistance through Cyclopentadienyl-Iron Multidecker Molecules},
      booktitle = {The Journal of Physical Chemistry C},
      journal = {J. Phys. Chem. C},
      publisher = {American Chemical Society},
      year = {2012},
      volume = {116},
      number = {37},
      pages = {19996--20001},
      doi = {http://dx.doi.org/10.1021/jp300465e}
    }
    
    Zhi Yang, Shaoding Liu, Xuguang Liu, Yongzhen Yang, Xiuyan Li, Shijie Xiong & Bingshe Xu The spin-filter capability and spin-reversal effect of multidecker iron-borazine sandwich cluster 2012 Applied Physics Letters
    Vol. 101(10), 102405 
    DOI  
    Abstract: Using density functional theory and non-equilibrium Green's function technique, we performed theoretical investigations on the magnetic and transport properties of Fe_n(B3N3H6)_(n+1) (n=1-4) sandwich clusters. The calculated results show that the clusters possess high magnetic moments owing to the unpaired d_delta electrons. Furthermore, high spin-filter capability, negative differential resistance, and spin-reversal effect were found in the systems, and the possible physical origination of the phenomena was suggested. Our findings also indicate that the magnetic or electrical properties of the system could be controlled by cluster size, and these sandwich clusters are promising materials for application in molecular electronics or spintronics.
    Keywords: ATK; Application; density functional theory; electrical resistivity; gold; Green's function methods; iron compounds; magnetic moments; M-I-M; MIM; sandwich structures; molecular wires; transport; magnetism
    Area: molecular electronics; spin
    BibTeX:
    @article{Yang2012a,
      author = {Yang, Zhi and Liu, Shaoding and Liu, Xuguang and Yang, Yongzhen and Li, Xiuyan and Xiong, Shijie and Xu, Bingshe},
      title = {The spin-filter capability and spin-reversal effect of multidecker iron-borazine sandwich cluster},
      journal = {Applied Physics Letters},
      publisher = {AIP},
      year = {2012},
      volume = {101},
      number = {10},
      pages = {102405},
      doi = {http://dx.doi.org/10.1063/1.4751340}
    }
    
    Jun You, Jun He, Ming-Ming Yin, Li-Ming Tang, Ke-Qiu Chen & Zhi-Qiang Fan The E-Z photo-isomerization switching behavior in single molecular device with carbon nanotube electrodes 2012 Computational Materials Science
    Vol. 65(0), 203-206 
    DOI  
    Abstract: By using nonequilibrium Green's functions in combination with the density-functional theory, we investigate the electronic transport properties of the molecular device constructed by a single 4,4-(ethene-1,2-diyl) dibenzoic acid sandwiched between carbon nanotube electrodes. The results show that an obvious reversible switching behavior can be observed when the molecular structure changes between E isomerization and Z isomerization by ultraviolet irradiation or visible irradiation. More importantly, the switching ratio can reach to a maximum (about 7000) at 0.28 V and then decrease gradually to a minimum at 0.48 V. It is suggested that the controllable switching behavior is very useful for the design of functional molecular devices.
    Keywords: electronic transport; single molecular device; switching behavior; nanotube; ATK; Application; switching; rectification
    Area: molecular electronics
    BibTeX:
    @article{You2012,
      author = {You, Jun and He, Jun and Yin, Ming-Ming and Tang, Li-Ming and Chen, Ke-Qiu and Fan, Zhi-Qiang},
      title = {The E-Z photo-isomerization switching behavior in single molecular device with carbon nanotube electrodes},
      journal = {Computational Materials Science},
      year = {2012},
      volume = {65},
      number = {0},
      pages = {203--206},
      doi = {http://dx.doi.org/10.1016/j.commatsci.2012.07.022}
    }
    
    C.X. Zhang, Chaoyu He, Lin Xue, K.W. Zhang, L.Z. Sun & Jianxin Zhong Transport properties of zigzag graphene nanoribbons with oxygen edge decoration 2012 Organic Electronics
    Vol. 13(11), 2494-2501 
    DOI  
    Abstract: Using the density functional theory in combination with the nonequilibrium Green's function method, we investigate the transport properties of zigzag-edged graphene nanoribbons (ZGNRs) with oxygen edge decoration (passivated by the ketone (C=O) or ether (C-O-C), denoting as ZGNR-CO and ZGNR-C2O, respectively). We find that both ZGNR-CO and ZGNR-C2O induce the semiconductor-metal transition and enhance the transmission conductance within "transparent" electrodes. However, sandwiched by Au (111) electrodes, Au|ZGNR - CO|Au enhances the transport properties while Au|ZGNR - C2O|Au depresses the transport properties in comparison with Au|ZGNR - H|Au. It is found that the transport properties of the edge oxidized ZGNRs within Au (111) electrodes depend on the electronic states around the Fermi level which determine the number of the effective transport channels. The states of Au|ZGNR - CO|Au are delocalized on the edge oxygen atoms as well as the inner edge carbon atoms, introducing extra transport channels. Moreover, in comparison with Au|ZGNR - H|Au, the effective transport channels of Au|ZGNR - CO|Au increase at given applied bias. However, the states of Au|ZGNR - C2O|Au are localized on the ribbon, blocking the effective transport channels.
    Keywords: zigzag-edged graphene nanoribbons; edge oxidization; transport properties; ATK; Application
    Area: graphene
    BibTeX:
    @article{Zhang2012e,
      author = {Zhang, C.X. and He, Chaoyu and Xue, Lin and Zhang, K.W. and Sun, L.Z. and Zhong, Jianxin},
      title = {Transport properties of zigzag graphene nanoribbons with oxygen edge decoration},
      journal = {Organic Electronics},
      year = {2012},
      volume = {13},
      number = {11},
      pages = {2494--2501},
      doi = {http://dx.doi.org/10.1016/j.orgel.2012.06.041}
    }
    
    Jiming Zheng, Ping Guo, Zhaoyu Ren, Zhenyi Jiang, Jintao Bai & Zhiyong Zhang Conductance fluctuations as a function of sliding motion in bilayer graphene nanoribbon junction: A first-principles investigation 2012 Applied Physics Letters
    Vol. 101(8), 083101 
    DOI  
    Abstract: A bilayer graphene nanoribbon based strain sensor is designed and investigated via first principles simulations. The interlayer sliding induces dramatically oscillation of current in order of several magnitudes. Electronic structure analysis attributes this oscillation of current to periodic variation of HOMO-LUMO gap which comes from the periodic change of interlayer stacking configuration. This kind of behaviors could potentially be implemented in future strain sensor and other nanoelectronic devices.
    Keywords: ATK; Application; ab initio calculations; current fluctuations; electric admittance; electronic structure; graphene; molecular electronics; nanoelectronics; nanostructured materials
    Area: graphene
    BibTeX:
    @article{Zheng2012b,
      author = {Zheng, Jiming and Guo, Ping and Ren, Zhaoyu and Jiang, Zhenyi and Bai, Jintao and Zhang, Zhiyong},
      title = {Conductance fluctuations as a function of sliding motion in bilayer graphene nanoribbon junction: A first-principles investigation},
      journal = {Applied Physics Letters},
      publisher = {AIP},
      year = {2012},
      volume = {101},
      number = {8},
      pages = {083101},
      doi = {http://dx.doi.org/10.1063/1.4739838}
    }
    
    X.H. Zheng, J. Lan, X.L. Wang, L.F. Huang, H. Hao & Z. Zeng Orbital symmetry induced conductance switching in a graphene nanoribbon heterojunction with different edge hydrogenations 2012 Appl. Phys. Lett.
    Vol. 101(5), 053101-4 
    DOI  
    Abstract: First principles calculations are performed to investigate the electron transport through a zigzag-edged graphene nanoribbon (ZGNR) heterojunction constructed by connecting a monohydrogenated ZGNR and a dihydrogenated ZGNR and its response to external magnetic fields. It is found that the heterojunction can be switched between a conducting state and an insulating state by tuning the magnetic fields. It arises from the matching or mismatching between the pi or pi* states of the two ribbons under different magnetic fields. This mechanism of conductance switching by tuning the orbital symmetry can be considered in the future design of graphene based electronic devices.
    Keywords: ATK; Application; ab initio calculations; electrical conductivity transitions; graphene; hydrogenation; nanoribbons; tuning; spin; half-metallicity; ribbons; stability
    Area: graphene; spin
    BibTeX:
    @article{Zheng2012c,
      author = {Zheng, X. H. and Lan, J. and Wang, X. L. and Huang, L. F. and Hao, H. and Zeng, Z.},
      title = {Orbital symmetry induced conductance switching in a graphene nanoribbon heterojunction with different edge hydrogenations},
      journal = {Appl. Phys. Lett.},
      publisher = {AIP},
      year = {2012},
      volume = {101},
      number = {5},
      pages = {053101--4},
      doi = {http://dx.doi.org/10.1063/1.4739938}
    }
    
    Fan Zhi-Qiang, Zhang Zhen-Hua, Qiu Ming, Deng Xiao-Qing & Tang Gui-Ping Controllable Negative Differential Resistance Behavior of an Azobenzene Molecular Device Induced by Different Molecule-Electrode Distances 2012 Chinese Physics Letters
    Vol. 29(7), 077305- 
    DOI URL 
    Abstract: Abstract: We report the ab initio calculations of transport behaviors of an azobenzene molecular device which is similar to the experimental configurations. The calculated results show that the transport behaviors of the device are sensitive to the molecule-electrode distance and the currents will drop rapidly when the molecule-electrode distance changes from 1.7 Å to 2.0 Å. More interestingly, the negative differential resistance behavior can be found in our device. Nevertheless, it is not the inherent property of an azobenzene molecular device but an effect of the molecule-electrode distance. Detailed analyses of the molecular projected self-consistent Hamiltonian states and the transmission spectra of the system reveal the physical mechanism of these behaviors.
    Keywords: ATK; Application; molecular electronics; MPSH analysis
    Area: molecular electronics
    BibTeX:
    @article{Zhi-Qiang2012,
      author = {Zhi-Qiang, Fan and Zhen-Hua, Zhang and Ming, Qiu and Xiao-Qing, Deng and Gui-Ping, Tang},
      title = {Controllable Negative Differential Resistance Behavior of an Azobenzene Molecular Device Induced by Different Molecule-Electrode Distances},
      journal = {Chinese Physics Letters},
      year = {2012},
      volume = {29},
      number = {7},
      pages = {077305--},
      url = {http://stacks.iop.org/0256-307X/29/i=7/a=077305},
      doi = {http://dx.doi.org/10.1088/0256-307X/29/7/077305}
    }
    
    Li-Ping An & Nian hua Liu The spin-dependent transport properties of zigzag graphene nanoribbon edge-defect junction 2012 New Carbon Materials
    Vol. 27(3), 181-187 
    DOI  
    Abstract: First-principles calculation was performed to investigate the transport properties of edge-defect junctions of graphene with H-terminated or bare edges, which were generated by removing edge carbon atoms from a perfect ribbon. The edge defect changes the electronic transport behavior of a zigzag graphene nanoribbon from spin-degenerated for a perfect ribbon to highly spin-polarized for edge-defective ones at the Fermi level. The electronic local density of states isosurface calculations could help understand the transport results. These junctions could generate spin-polarized currents. Especially, the bare edge-defect junction has a high spin filter efficiency regardless of the external bias. This behavior suggests a possible use of the edge-defective graphene in a spin filter system.
    Keywords: graphene nanoribbon; edge-defect junction; spin-dependent transport; ATK; Application
    Area: graphene; spin
    BibTeX:
    @article{An2012b,
      author = {An, Li-Ping and Liu, Nian-hua},
      title = {The spin-dependent transport properties of zigzag graphene nanoribbon edge-defect junction},
      journal = {New Carbon Materials},
      year = {2012},
      volume = {27},
      number = {3},
      pages = {181--187},
      doi = {http://dx.doi.org/10.1016/S1872-5805(12)60012-2}
    }
    
    Can Cao, Ling-Na Chen, Meng-Qiu Long, Wei-Rong Huang & Hui Xu Electronic transport properties on transition-metal terminated zigzag graphene nanoribbons 2012 Journal of Applied Physics
    Vol. 111(11), 113708 
    DOI  
    Abstract: By using non-equilibrium Green's functions in combination with the density-functional theory, we investigate the spin transport properties of molecular junctions based on 3d transition terminated zigzag graphene nanoribbons. The results show that the electronic transport properties are strongly depending on the type of terminated atom at the edge of ribbon. The currents of spin-up and spin-down display different behaviors, and the spin-filter effects can be observed. These unconventional doping effects could be used to design novel nanospintronics devices.
    Keywords: density functional theory; doping; Fermi level; graphene; Green's function methods; nanoribbons; spin polarised transport; ATK; Application
    Area: graphene spin
    BibTeX:
    @article{Cao2012b,
      author = {Can Cao and Ling-Na Chen and Meng-Qiu Long and Wei-Rong Huang and Hui Xu},
      title = {Electronic transport properties on transition-metal terminated zigzag graphene nanoribbons},
      journal = {Journal of Applied Physics},
      publisher = {AIP},
      year = {2012},
      volume = {111},
      number = {11},
      pages = {113708},
      doi = {http://dx.doi.org/10.1063/1.4723832}
    }
    
    M. Chakraverty & H.M. Kittur Evidence of hysteresis from first principle DFT simulations of I-V curves in Pt/TiO(2-x) - TiO2/Pt memristive systems 2012 Devices, Circuits and Systems (ICDCS), 2012 International Conference on, 379-383  DOI  
    Abstract: The memristor is an electrical circuit element that is similar to a resistor but has the potential to maintain state between turning power on and off. These memristors are about half the size of the transistors found in current flash storage technology, allowing capacity of these devices to double. This paper discusses the basics of memristors, which is an electrical circuit element, and presents the first principle simulation results of Pt/TiO2-x - TiO2/Pt system where the central region has a boundary separating TiO2-x and TiO2 regions. This barrier is progressively shifted towards the TiO2-x region with applied bias to gradually increase the thickness of TiO2 region. A comparison of the electrical characteristics of the device when the TiO2 region is extended towards TiO2-x region is also presented. The basis of memristive behavior, the nonlinear hysteresis curve of memristor, has been obtained based upon the simulation results.
    Keywords: memristors; platinum; titanium compounds; I-V curves; Pt-TiO2-x-TiO2-Pt; electrical characteristics; electrical circuit element; first principle DFT simulations; flash storage technology; memristive systems; memristor; nonlinear hysteresis curve; transistors; DRAM; hysteresis; ATK; Application
    Area: interfaces
    BibTeX:
    @inproceedings{Chakraverty2012,
      author = {Chakraverty, M. and Kittur, H.M.},
      title = {Evidence of hysteresis from first principle DFT simulations of I-V curves in Pt/TiO(2-x) - TiO2/Pt memristive systems},
      booktitle = {Devices, Circuits and Systems (ICDCS), 2012 International Conference on},
      year = {2012},
      pages = {379--383},
      doi = {http://dx.doi.org/10.1109/ICDCSyst.2012.6188749}
    }
    
    Bagavathi Chandrasekara & K A Narayanankutty Gallium Nitride Nanotube and its Application as Transistors 2012 International Journal of Computer Applications
    Vol. 47, 0975-888 
    DOI URL 
    Abstract: In search of opto-electronic nano materials, we often come across Gallium Nitride nanotubes (GaN-NT) with excellent electrical and optical characteristics. Gallium Nitride nanotubes are predominantly semiconducting and have been less explored in its application as a transistor channel through Density Functional Theory (DFT). Comparing Gallium Nitride nanotubes with Boron Nitride nanotubes (BN-NT) and Carbon nanotubes (CNT), we have obtained distinguishing features of Gallium Nitride nanotubes. In this work, Transistor simulation with Gallium Nitride nanotubes has been reported with the nanotube as channel. Properties of various configurations of nanotubes are compared among Carbon, Boron Nitride and Gallium Nitride nanotubes.
    Keywords: ATK; Application; Gallium Nitride nanotubes; GaN nanotube transistor; Density Functional Theory (DFT); bond rotation; Boron Nitride nanotubes
    Area: nanotubes
    BibTeX:
    @article{Chandrasekara2012,
      author = {Bagavathi Chandrasekara and K A Narayanankutty},
      title = {Gallium Nitride Nanotube and its Application as Transistors},
      journal = {International Journal of Computer Applications},
      year = {2012},
      volume = {47},
      pages = {0975-888},
      url = {http://www.ijcaonline.org/archives/volume47/number14/7259-0347},
      doi = {http://dx.doi.org/10.5120/7259-0347}
    }
    
    Satyendra Singh Chauhan, Pankaj Srivastava & Ashwani Kumar Shrivastava Band Gap Engineering in Zigzag Graphene NanoribbonsAn Ab Initio Approach 2012 Journal of Computational and Theoretical Nanoscience
    Vol. 9(8), 1084-1089 
    DOI  
    Abstract: We present first principles study based on spin polarized density functional theory for electronic properties of armchair graphene nanoribbons (AGNRs) and Bloch state study in zigzag graphene nanoribbons (ZGNRs) passivated with hydrogen atoms. We have investigated the spin-dependent band structure of zigzag graphene nanoribbons. It is observed that these zigzag ribbons are metallic without spin consideration while band gap opens up when spin included. We have also plotted conduction and valence band Bloch states for various k-points and observed that the two spincomponents are localized on opposite sides of the ribbon.
    Keywords: armchair; zigzag; band gap; electronic properties; stability; Bloch states; ATK; Application
    Area: graphene; spin
    BibTeX:
    @article{Chauhan2012,
      author = {Chauhan, Satyendra Singh and Srivastava, Pankaj and Shrivastava, Ashwani Kumar},
      title = {Band Gap Engineering in Zigzag Graphene NanoribbonsAn Ab Initio Approach},
      journal = {Journal of Computational and Theoretical Nanoscience},
      year = {2012},
      volume = {9},
      number = {8},
      pages = {1084--1089},
      doi = {http://dx.doi.org/10.1166/jctn.2012.2147}
    }
    
    R. Chowdhury Conductance of graphene nanoribbons under mechanical deformation 2012 Physica E: Low-dimensional Systems and Nanostructures
    Vol. 44(7-8), 1256-1259 
    DOI URL 
    Abstract: Graphene is a material system of increasing technological importance with excellent mechanical and electrical properties. Depending on the edge configuration, graphene may be electrically conducting, semiconducting, or insulating, so deformation is believed to have strong effects on electrical properties. In this letter, ab initio approach is used to demonstrate the effect of torsional and strain induced deformation on the electrical conductance characteristics. These nanostructures are described using a single-band tight-binding Hamiltonian. Important observations on the connection between mechanical and electrical behavior are made based on the transport calculations. In particular, the conductance behavior shows interesting features on deformed graphene.
    Keywords: ATK; Application; graphene nanoribbon; mechanical properties;
    Area: graphene
    BibTeX:
    @article{Chowdhury2012a,
      author = {Chowdhury, R.},
      title = {Conductance of graphene nanoribbons under mechanical deformation},
      journal = {Physica E: Low-dimensional Systems and Nanostructures},
      year = {2012},
      volume = {44},
      number = {7-8},
      pages = {1256--1259},
      url = {http://www.sciencedirect.com/science/article/pii/S1386947712000379},
      doi = {http://dx.doi.org/10.1016/j.physe.2012.01.023}
    }
    
    R. Chowdhury, F. Scarpa & S. Adhikari Molecular-scale bio-sensing using armchair graphene 2012 Journal of Applied Physics
    Vol. 112(1), 014905 
    DOI  
    Abstract: We evaluate the transport properties performance of armchair graphene nanoribbons (AGNRs) with a bio-molecule assembly as potential molecular-scale biosensors (Anthracene). The bio-molecules are assumed to be absorbed at the edge of an AGNR, and to behave as quasi-1D systems. The transport spectrum and density of states (DOS) are calculated using a single-band tight-binding Hamiltonian representation, and a non-equilibrium Greens function formalism. Doping with boron and nitride atoms and its impact on the transport properties has also been evaluated. Significant changes in transmission and increase in DOS by 200% are observed when the Anthracene molecule is interacting with the AGNR. Boron and Nitrogen doping allow to increase current flows at constant voltage by 50% on average. There results suggest potential significant scope on using AGNRs for bio-devices based on either conductance or electroluminescence.
    Keywords: adsorption; biological techniques; biosensors; boron; doping; electrical conductivity; electroluminescence; electronic density of states; fullerene devices; graphene; Green's function methods; molecular biophysics; nanoribbons; nanosensors; nitrogen; organic semiconductors; tight-binding calculations; ATK; Application
    Area: graphene
    BibTeX:
    @article{Chowdhury2012b,
      author = {R. Chowdhury and F. Scarpa and S. Adhikari},
      title = {Molecular-scale bio-sensing using armchair graphene},
      journal = {Journal of Applied Physics},
      publisher = {AIP},
      year = {2012},
      volume = {112},
      number = {1},
      pages = {014905},
      doi = {http://dx.doi.org/10.1063/1.4733689}
    }
    
    Bidisa Das & Somobrata Acharya Effect of Point Defects and Impurities on the Electronic Transport of Au Tipped Ultranarrow PbS Nanorods 2012 Journal of Nanoscience and Nanotechnology
    Vol. 12(8), 6258-6264 
    DOI  
    Abstract: Electronic transport through single nanowire/nanorod directly probes the fundamental limits of semiconductor device miniaturization. Point defects or impurity centers form easily during the growth of nanorods/nanowires which may strongly affect the electronic transport efficiencies. Existing models of electronic transport are often unable to determine the role of defects and impurities at the nanoscale because there are significant differences between nanostructures and bulk materials arising from unique geometries and confinement. The effect of defect and impurities on the conductance of a model ultranarrow PbS rod was modeled using density functional theory. It was observed that the introduction of defects and Au impurities modified the orbital energies of PbS nanorods and reduced the conductance compared to the defect-free rod. The conductance for the nanorods with defects and impurities were limited by the number of available conduction channels required for efficient electronic conduction.
    Keywords: ATK; Application; nanowire; colloidal semiconductor nanorods; selective growth; metal tips; rods; conductance
    Area: nanowires
    BibTeX:
    @article{Das2012,
      author = {Das, Bidisa and Acharya, Somobrata},
      title = {Effect of Point Defects and Impurities on the Electronic Transport of Au Tipped Ultranarrow PbS Nanorods},
      journal = {Journal of Nanoscience and Nanotechnology},
      year = {2012},
      volume = {12},
      number = {8},
      pages = {6258--6264},
      doi = {http://dx.doi.org/10.1166/jnn.2012.6210}
    }
    
    Hiroyuki Fueno, Yoshikazu Kobayashi & Kazuyoshi Tanaka Theoretical study of current-voltage characteristics of carbon nanotube wire functionalized with hydrogen atoms 2012 SCIENCE CHINA Chemistry
    Vol. 55(5), 796-801 
    URL 
    Abstract: A functionalized single-walled carbon nanotube (SWCNT) of a finite length with a ring-like hydrogenation around its surface is designed toward fabrication of a molecular field-effect transistor (FET) device. The molecular wire thus designed is equipped with a quantum dot inside, which is confirmed by theoretical analysis for electronic transport. In particular, the current-voltage (I-V) characteristics under influence of the gate voltage are discussed in detail.
    Keywords: ATK; Application; nanotube; molecular field-effect transistor; FET; device
    Area: nanotubes
    BibTeX:
    @article{Fueno2012,
      author = {Fueno, Hiroyuki and Kobayashi, Yoshikazu and Tanaka, Kazuyoshi},
      title = {Theoretical study of current-voltage characteristics of carbon nanotube wire functionalized with hydrogen atoms},
      journal = {SCIENCE CHINA Chemistry},
      publisher = {Science China Press, co-published with Springer},
      year = {2012},
      volume = {55},
      number = {5},
      pages = {796--801},
      url = {10.1007/s11426-012-4499-8}
    }
    
    Tingkun Gu, Tomofumi Tada & Satoshi Watanabe Conductive Path Formation in the Ta2O5 Atomic Switch: First-Principles Analyses 2010 ACS Nano
    Vol. 4(11)ACS Nano, 6477-6482 
    DOI  
    Abstract: The conductive path formed by the interstitial Cu or oxygen vacancies in the Ta2O5 atomic switch were investigated in detail by first-principles methods. The calculated results indicated that the defect state induced by the interstitial Cu is located just at the Fermi level of the Cu and Pt electrodes in the Cu/Ta2O5/Pt heterostructure and that a conduction channel is formed in the Ta2O5 film via the interstitial Cu. On the other hand, oxygen vacancies in Ta2O5 do not form such a conduction channel because of the lower energy positions of their defect states. The above results suggest that the conductive path could be formed by interstitial Cu in the Ta2O5 atomic switch, whereas the oxygen vacancies do not contribute to the formation of the conductive path.
    Keywords: ab initio calculations; copper; density functional theory; energy gap; Green's function methods; metal-insulator boundaries; platinum; Schottky barrier height (SBH); tantalum compounds; ATK; Application; interfaces; resistive switch;
    Area: interfaces, semi
    BibTeX:
    @article{Gu2010,
      author = {Gu, Tingkun and Tada, Tomofumi and Watanabe, Satoshi},
      title = {Conductive Path Formation in the Ta2O5 Atomic Switch: First-Principles Analyses},
      booktitle = {ACS Nano},
      journal = {ACS Nano},
      publisher = {American Chemical Society},
      year = {2010},
      volume = {4},
      number = {11},
      pages = {6477--6482},
      doi = {http://dx.doi.org/10.1021/nn101410s}
    }
    
    C. Guo, Z.H. Zhang, G. Kwong, J.B. Pan, X.Q. Deng & J.J. Zhang Enormously Enhanced Rectifying Performances by Modification of Carbon Chains for D-sigma-A Molecular Devices 2012 J. Phys. Chem. C
    Vol. 116(23)The Journal of Physical Chemistry C, 12900-12905 
    DOI  
    Abstract: By using the carbon chain as the end group attached to either the left or right side or both sides of the D-sigma-A molecule, we investigate theoretically its rectifying performance. Interestingly, the currently reported highest rectification ratio, 408, with the density functional calculations for a unimolecule device with metal electrodes can be obtained when both carbon chains are symmetrically attached to both sides of the D-sigma-A molecule. Our finding implies that to greatly promote rectifying characteristics of the D-sigma-A molecule the suitable end-group engineering might be a key issue, and increasing geometrical asymmetries of a molecule may not be the only effective way.
    Keywords: ATK; Application; molecular electronics; rectification
    Area: molecular electronics
    BibTeX:
    @article{Guo2012,
      author = {Guo, C. and Zhang, Z. H. and Kwong, G. and Pan, J. B. and Deng, X. Q. and Zhang, J. J.},
      title = {Enormously Enhanced Rectifying Performances by Modification of Carbon Chains for D-sigma-A Molecular Devices},
      booktitle = {The Journal of Physical Chemistry C},
      journal = {J. Phys. Chem. C},
      publisher = {American Chemical Society},
      year = {2012},
      volume = {116},
      number = {23},
      pages = {12900--12905},
      doi = {http://dx.doi.org/10.1021/jp302254f}
    }
    
    Jing Huang, Weiyi Wang, Shangfeng Yang, Haibin Su, Qunxiang Li & Jinlong Yang A theoretical study of spin-polarized transport properties of planar four-coordinate Fe complexes 2012 Chemical Physics Letters
    Vol. 539-540(0), 102-106 
    DOI  
    Abstract: We present a first-principles study of the spin-polarized transport properties of three planar four-coordinate Fe complexes with different noninnocent ligands sandwiched between two armchair (5,5) single-walled carbon nanotube (SWCNT) electrodes. Theoretical results clearly reveal that the current of the spin-up electrons through three examined molecular junctions is significant larger than that of the spin-down electrons. The low bias conductance is determined by the tail of transmission peak coming from the perturbed lowest unoccupied molecular orbital of the spin-up electrons. The high spin-filter efficiencies (up to 99.0%) are predicted for three planar four-coordinate Fe complexes coupled to SWCNTs.
    Keywords: ATK; Application; molecular electronics; nanotube; spin
    Area: molecular electronics; nanotubes; spin
    BibTeX:
    @article{Huang2012a,
      author = {Huang, Jing and Wang, Weiyi and Yang, Shangfeng and Su, Haibin and Li, Qunxiang and Yang, Jinlong},
      title = {A theoretical study of spin-polarized transport properties of planar four-coordinate Fe complexes},
      journal = {Chemical Physics Letters},
      year = {2012},
      volume = {539-540},
      number = {0},
      pages = {102--106},
      doi = {http://dx.doi.org/10.1016/j.cplett.2012.05.002}
    }
    
    Jing Huang, Weiyi Wang, Shangfeng Yang, Qunxiang Li & Jinlong Yang Efficient spin filter based on FeN_4 complexes between carbon nanotube electrodes 2012 Nanotechnology
    Vol. 23(25), 255202 
    DOI URL 
    Abstract: We present a theoretical study to explore the spin transport properties of FeN 4 complexes sandwiched between two armchair (5, 5) carbon nanotube (CNT) electrodes. The ab-initio modeling is performed by combining the spin-dependent density functional theory with nonequilibrium Green's function formalism. The calculated results clearly demonstrate that the transport properties of FeN 4 complexes are sensitive to the contact configuration. Near the Fermi level the conductance through three examined junctions is mainly governed by the spin-up electrons. The FeN 4 complex coupled to CNT electrodes with the pi-type contact conjugation can act as a nearly perfect spin filter, and its spin filter efficiency is up to 98.0%. Our theoretical results demonstrate that FeN 4 complexes are promising for future molecular spintronics devices.
    Keywords: spin; nanotube; ATK; Application; spin filtering; spintronics
    Area: nanotubes; spin
    BibTeX:
    @article{Huang2012b,
      author = {Jing Huang and Weiyi Wang and Shangfeng Yang and Qunxiang Li and Jinlong Yang},
      title = {Efficient spin filter based on FeN_4 complexes between carbon nanotube electrodes},
      journal = {Nanotechnology},
      year = {2012},
      volume = {23},
      number = {25},
      pages = {255202},
      url = {http://stacks.iop.org/0957-4484/23/i=25/a=255202},
      doi = {http://dx.doi.org/10.1088/0957-4484/23/25/255202}
    }
    
    Neeraj K. Jaiswal & Pankaj Srivastava First principles calculations of cobalt doped zigzag graphene nanoribbons 2012 Solid State Communications
    Vol. 152(15)Exploring Graphene, Recent Research Advances, 1489-1492 
    DOI URL 
    Abstract: We have investigated the stability and electronic properties of Co-doped zigzag graphene nanoribbons (ZGNR) by employing first principles calculations based on density functional theory. The results show that Co impurities settled in antiferromagnetic ground state which is ~2 meV favourable than ferromagnetic state. The formation energy indicates spontaneous formation of one-edge and centre doped structures, however, one-edge doping is found to be the most energetically favourable configuration. A charge transfer takes place from C to Co atoms which shows the formation of chemical bonding between C and Co. Binding energy also confirms the strong bonding of dopant Co impurity with C. The calculations show that band structures of all the ZGNR is substantially modified due to Co-C charge transfer and the characteristic edge states of ZGNR are completely lost. Co-doping induces site independent enhanced metallicity irrespective of the ribbon widths. The broken degeneracy of electronic states in one-edge and centre doped ZGNR is important for spintronic applications.
    Keywords: graphene nanoribbon; doping; electronic band structure; ATK; Application; spin
    Area: graphene; spin
    BibTeX:
    @article{Jaiswal2012a,
      author = {Jaiswal, Neeraj K. and Srivastava, Pankaj},
      title = {First principles calculations of cobalt doped zigzag graphene nanoribbons},
      booktitle = {Exploring Graphene, Recent Research Advances},
      journal = {Solid State Communications},
      year = {2012},
      volume = {152},
      number = {15},
      pages = {1489--1492},
      url = {http://www.sciencedirect.com/science/article/pii/S0038109812002530},
      doi = {http://dx.doi.org/10.1016/j.ssc.2012.04.047}
    }
    
    V K Lamba & D Engles Modifying the Electronic Properties of Nano-Structures Using Strain 2012 Journal of Physics: Conference Series
    Vol. 377(1), 012069 
    DOI  
    Abstract: We used density-functional theory based Non equilibrium green function simulations to study the effects of strain and quantum confinement on the electronic properties of Germanium & Silicon NWs along the [110] direction, such as the energy gap and the effective masses of the electron and hole. The diameters of the NWs being studied in a range of 3-20 Å. On basis of our calculation we conclude that the Ge [110] NWs possess a direct band gap, while Si [110] NWs possess indirect band gap at nanoscale. The band gap is almost a linear function of strain when the diameter of Ge NWs D < 10 Å while shows parabolic behaviour for, D > 15 Å; & for Si it is linear in behaviour. On doping silicon wire we found that the bandgap shows parabolic behaviour for change in strain. We also concluded that the band gap and the effective masses of charge carries (i.e. electron & hole) changes by applying the strain to the NWs. Our results suggested that strain can be used to tune the ba nd structures of NWs, which may help in de sign of future nanoelectronic devices.
    Keywords: ATK; Application; strain; nanowire;
    Area: nanowires
    BibTeX:
    @article{Lamba2012,
      author = {V K Lamba and D Engles},
      title = {Modifying the Electronic Properties of Nano-Structures Using Strain},
      journal = {Journal of Physics: Conference Series},
      year = {2012},
      volume = {377},
      number = {1},
      pages = {012069},
      doi = {http://dx.doi.org/10.1088/1742-6596/377/1/012069}
    }
    
    Hong Li, Nabil Al-Aqtash, Lu Wang, Rui Qin, Qihang Liu, Jiaxin Zheng, Wai-Ning Mei, R.F. Sabirianov, Zhengxiang Gao & Jing Lu Electromechanical switch in metallic graphene nanoribbons via twisting 2012 Physica E: Low-dimensional Systems and Nanostructures
    Vol. 44(10), 2021-2026 
    DOI  
    Abstract: We imposed screwing operation to a metallic ferromagnetic zigzag-edged graphene nanoribbon (ZGNR) with a narrow width and a finite length, and the polarized charge transport is investigated by using Nonequilibrium Green's function in combination with density functional theory. The current are nearly completely suppressed when the ZGNRs are overturned. Inspiringly, this metal-to-semiconductor transition tuned by screwing operation is reversible. Hence our investigation brings forward a novel electromechanical switch, and such a switch is equivalent to a spin valve without resort to an external magnetic field.
    Keywords: ATK; Application; mechanical; electromechanical; graphene nanoribbon;
    Area: graphene
    BibTeX:
    @article{Li2012g,
      author = {Li, Hong and Al-Aqtash, Nabil and Wang, Lu and Qin, Rui and Liu, Qihang and Zheng, Jiaxin and Mei, Wai-Ning and Sabirianov, R.F. and Gao, Zhengxiang and Lu, Jing},
      title = {Electromechanical switch in metallic graphene nanoribbons via twisting},
      journal = {Physica E: Low-dimensional Systems and Nanostructures},
      year = {2012},
      volume = {44},
      number = {10},
      pages = {2021--2026},
      doi = {http://dx.doi.org/10.1016/j.physe.2012.06.004}
    }
    
    Enling Li, Liping Hou, Zhen Cui, Danna Zhao, Mancang Liu & Xuewen Wang Electronic structures and transport properties of single crystalline GaN nanotubes 2012 Nano
    Vol. 07(03)Nano, 1250014 
    DOI  
    Abstract: The electronic structures and transport properties of single crystalline GaN nanotubes with 0.92 nm inner diameter and different wall thicknesses of 0.08 nm, 0.26 nm and 0.54 nm are studied based on the generalized gradient approximation (GGA) of density functional theory (DFT) and the nonequilibrium green's function (NEGF). The research shows that (1) the three single crystalline GaN nanotubes have direct band gaps, decreasing with the increase of wall thickness; (2) the electronic density of state and electronic transmission spectra of two-probe system have their own pulse-type sharp peaks with almost the same location of electron energy; (3) under different bias-voltages, two-probe systems of the single crystalline GaN nanotubes have the I-V properties which reveal that the single-wall GaN nanotube and the single-layer GaN nanotube are semiconducting and the double-layer GaN nanotube appears nearly metallic.
    Keywords: ATK; Application; GaN nanotubes; electronic transport; density functional theory (DFT);
    Area: nanotubes
    BibTeX:
    @article{Li2012h,
      author = {Li, Enling and Hou, Liping and Cui, Zhen and Zhao, Danna and Liu, Mancang and Wang, Xuewen},
      title = {Electronic structures and transport properties of single crystalline GaN nanotubes},
      booktitle = {Nano},
      journal = {Nano},
      publisher = {World Scientific Publishing Co.},
      year = {2012},
      volume = {07},
      number = {03},
      pages = {1250014},
      doi = {http://dx.doi.org/10.1142/S1793292012500142}
    }
    
    J. Li, Z.H. Zhang, J.J. Zhang & X.Q. Deng Rectifying regularity for a combined nanostructure of two trigonal graphenes with different edge modifications 2012 Organic Electronics
    Vol. 13(11), 2257-2263 
    DOI  
    Abstract: The metal- or nonmetal-terminated left zigzag-edge trigonal graphene (M-LTGN or NM-LTGN) is linked to the H-terminated right zigzag-edge trigonal graphene (H-RTGN) through their vertex atoms wholly attached onto Au electrodes to construct nanojunctions. Calculated results show that their rectifying behaviors have very interesting regularities: the rectifying directions for M-LTGN/H-RTGN nanojunction and NM-LTGN/H-RTGN nanojunction are opposite, and the stronger the nonmetallic (metallic) behavior for atom terminated at edge of the LTGN, the larger its rectification ratio for a forward (reverse) rectification. The intrinsic mechanism for these features can be attributed to a Schottky barrier on interface when they are combined due to the charge shifting doping between them. Findings unveiled here are of importance for achieving a profound understanding and developing nanoelectronic devices on the TGN functionalized by edge modification.
    Keywords: zigzag-edge trigonal graphene; edge modification; rectifying behavior; Schottky barrier; density-functional theory; ATK; Application
    Area: molecular electronics; graphene
    BibTeX:
    @article{Li2012i,
      author = {Li, J. and Zhang, Z.H. and Zhang, J.J. and Deng, X.Q.},
      title = {Rectifying regularity for a combined nanostructure of two trigonal graphenes with different edge modifications},
      journal = {Organic Electronics},
      year = {2012},
      volume = {13},
      number = {11},
      pages = {2257--2263},
      doi = {http://dx.doi.org/10.1016/j.orgel.2012.07.010}
    }
    
    E.L. Li, Z. Cui, M.C. Liu & X.W. Wang First-Principles Study on Transport Properties of Saturated Single Crystalline GaN Nanotubes 2012 Integrated Ferroelectrics
    Vol. 137, 134-142 
    DOI  
    Abstract: Electronic structures and transport properties of the saturated single crystalline GaN nanotubes with 0.92 nm inner diameter and different wall thickness have been investigated by using first-principles and non-equilibrium Green's function (NEGF). The result shows, the energy gap of the saturated single crystalline nanotubes changed from 0.2933 to 2.8442 eV. The saturated single crystalline GaN nanotubes have the direct band gap and the band gap decreases with the increase of wall thickness of nanotubes. The electronic density of state and the electronic transmission spectra of two-probe system have pulse-type sharp peak, the change of electronic density of state is in accord with electronic transmission rate. I-V characteristics of two-probe systems reflect that the saturated single-wall GaN nanotube and the saturated single-layer GaN nanotube are semiconducting properties, and the saturated double-layer GaN nanotube appears metallic behavior.
    Keywords: nanotubes; ATK; Application; GaN;
    Area: nanowires
    BibTeX:
    @article{Li2012j,
      author = {Li, E. L. and Cui, Z. and Liu, M. C. and Wang, X. W.},
      title = {First-Principles Study on Transport Properties of Saturated Single Crystalline GaN Nanotubes},
      journal = {Integrated Ferroelectrics},
      publisher = {Taylor & Francis Ltd},
      year = {2012},
      volume = {137},
      pages = {134--142},
      doi = {http://dx.doi.org/10.1080/10584587.2012.687319}
    }
    
    An Li-Ping, Liu Chun-Mei & Liu Nian-Hua Negative Differential Resistance in Atomic Carbon Chain-Graphene Junctions 2012 Communications in Theoretical Physics
    Vol. 57(6), 1087 
    DOI  
    Abstract: We investigate the electronic transport properties of atomic carbon chain-graphene junctions by using the density-functional theory combining with the non-equilibrium Green's functions. The results show that the transport properties are sensitively dependent on the contact geometry of carbon chain. From the calculated I-V curve we find negative differential resistance (NDR) in the two types of junctions. The NDR can be considered as a result of molecular orbitals moving related to the bias window.
    Keywords: ATK; Application; graphene; negative differential resistance; NDR
    Area: graphene
    BibTeX:
    @article{Li-Ping2012,
      author = {An Li-Ping and Liu Chun-Mei and Liu Nian-Hua},
      title = {Negative Differential Resistance in Atomic Carbon Chain-Graphene Junctions},
      journal = {Communications in Theoretical Physics},
      year = {2012},
      volume = {57},
      number = {6},
      pages = {1087},
      doi = {http://dx.doi.org/10.1088/0253-6102/57/6/25}
    }
    
    Xin Luo, Yue Zheng & Biao Wang First-principles calculations of size-dependent giant electroresistance effect in nanoscale asymmetric ferroelectric tunnel junctions 2012 Journal of Applied Physics
    Vol. 111(7), 074102 
    DOI  
    Abstract: Based on the first principle calculations, we predicted the electronic structures and ferroelectric instability of the asymmetric ferroelectric tunneling junction with the ferroelectric barrier thickness changing, and found two undiscovered and important behaviors, i.e., absence of the critical thickness for the positive polarization state and the larger critical thickness for the negative polarization state. Using nonequilibrium Green function's approach, the corresponding two-probe systems and their electronic transport properties at different ferroelectric barrier thickness have been constructed. It is found that reorienting the polarization direction in the ferroelectric barrier can dramatically change the internal electric field and macroscopic potential barrier, resulting in several orders of magnitude change in tunneling electroresistance ratio. Results also found that the tunneling electroresistance can be distinctly controlled by adjusting thickness of the ferroelectric barrier, which behavior is defined as the size-dependent giant electroresistance effect. Our results enable architectures of large density and high sensitivity in the next generation of ferroelectric random access memories with nondestructive resistive readout.
    Keywords: ab initio calculations; band structure; barium compounds; ferroelectric devices; ferroelectric materials; ferroelectric storage; ferroelectricity; Green's function methods; nanotechnology; platinum; random-access storage; strontium compounds; ATK; Application
    Area: interfaces
    BibTeX:
    @article{Luo2012,
      author = {Xin Luo and Yue Zheng and Biao Wang},
      title = {First-principles calculations of size-dependent giant electroresistance effect in nanoscale asymmetric ferroelectric tunnel junctions},
      journal = {Journal of Applied Physics},
      publisher = {AIP},
      year = {2012},
      volume = {111},
      number = {7},
      pages = {074102},
      doi = {http://dx.doi.org/10.1063/1.3698503}
    }
    
    JiaSai Ma, HaiMing Dong, DongMei Li & DeSheng Liu Negative differential resistance behaviors in OPE derivatives combined C60 molecular junctions modulated with side groups 2012 SCIENCE CHINA Physics, Mechanics & Astronomy
    Vol. 55, 1412-1416 
    DOI  
    Abstract: By applying non-equilibrium Green's functions (NEGF) in combination with the density functional theory (DFT), we investigate the electronic transport properties of molecular junctions constructed by OPE derivatives with different side groups combined C 60 molecules. The results show that the side groups play an important role in the properties of electron transport. Negative differential resistance (NDR) is observed in such devices. Especially for the molecule with electron-donating group (-OCH3), two NDR appear at different bias voltage regions. And the mechanism is proposed for the NDR behavior, owing to the shift of the molecular orbitals caused by the change in molecule charge.
    Keywords: self-assembled monolayers; device; negative differential resistance; NDR; electronic transport; non-equilibrium Green's function; side groups; molecular electronics; fullerenes; C60; OPE; ATK; Application
    Area: molecular electronics; fullerenes
    BibTeX:
    @article{Ma2012,
      author = {Ma, JiaSai and Dong, HaiMing and Li, DongMei and Liu, DeSheng},
      title = {Negative differential resistance behaviors in OPE derivatives combined C60 molecular junctions modulated with side groups},
      journal = {SCIENCE CHINA Physics, Mechanics & Astronomy},
      publisher = {Science China Press, co-published with Springer},
      year = {2012},
      volume = {55},
      pages = {1412-1416},
      note = {10.1007/s11433-012-4768-8},
      doi = {http://dx.doi.org/10.1007/s11433-012-4768-8}
    }
    
    Duan Man-Yi, Shi Guo-Sheng, Wang Chun-Lei, Zhou Li-Ping, Chen Xiang-Rong & Fang Hai-Ping A Theoretical Study of a Single-Walled ZnO Nanotube as a Sensor for H2O Molecules 2012 Communications in Theoretical Physics
    Vol. 58(2), 275 
    DOI URL 
    Abstract: We have studied the property of single-walled ZnO nanotubes with adsorbed water molecules, and theoretically designed a new sensor for detecting water molecules using single-walled ZnO nanotubes using a combination of density functional theory and the non-equilibrium Green's function method. Details of the geometric structures and adsorption energies of the H 2 O molecules on the ZnO nanotube surface have been investigated. Our computational results demonstrate that the formation of hydrogen bonding between the H 2 O molecules and the ZnO nanotube, and adsorption energies of the H 2 O molecules on the ZnO nanotube are larger than the adsorption energies of other gas molecules present in the atmospheric environment. Moreover, the current-voltage curves of the ZnO nanotube with and without H 2 O molecules adsorbed on its surface are calculated, the results of which showed that the H 2 O molecules form stable adsorption configurations that could lead to the decrease in current. These results suggest that the single-walled ZnO nanotubes are able to detect and monitor the presence of H 2 O molecules by applying bias voltages.
    Keywords: ATK; Application; ZnO nanotube; sensor; electronic-properties; magnetic-properties; adsorption; 1st-principles
    Area: nanotubes
    BibTeX:
    @article{Man-Yi2012,
      author = {Duan Man-Yi and Shi Guo-Sheng and Wang Chun-Lei and Zhou Li-Ping and Chen Xiang-Rong and Fang Hai-Ping},
      title = {A Theoretical Study of a Single-Walled ZnO Nanotube as a Sensor for H2O Molecules},
      journal = {Communications in Theoretical Physics},
      year = {2012},
      volume = {58},
      number = {2},
      pages = {275},
      url = {http://stacks.iop.org/0253-6102/58/i=2/a=18},
      doi = {http://dx.doi.org/10.1088/0253-6102/58/2/18}
    }
    
    Argo Nurbawono, Aihua Zhang, Yongqing Cai, Yihong Wu, Yuan Ping Feng & Chun Zhang Nanowelding of carbon nanotube-metal contacts: An effective way to control the Schottky barrier and performance of carbon nanotube based field effect transistors 2012 The Journal of Chemical Physics
    Vol. 136(17), 174704 
    DOI  
    Abstract: Schottky barriers formed at carbon nanotube (CNT)-metal contacts have been well known to be crucial for the performance of CNT based field effect transistors (FETs). Through first principles calculations we show that a nanowelding process can drastically reduce the Schottky barriers at CNT-metal interfaces, resulting in significantly improved conductivity of CNT-based FETs. The proposed nanowelding can be realized by either laser local heating or a heating process via a controllable pulse current. Results presented in this paper may have great implications in future design and applications of CNT-based electronics.
    Keywords: carbon nanotubes; field effect transistors; nanocontacts; nanofabrication; Schottky barriers; ATK; Application
    Area: nanotubes; interfaces
    BibTeX:
    @article{Nurbawono2012,
      author = {Argo Nurbawono and Aihua Zhang and Yongqing Cai and Yihong Wu and Yuan Ping Feng and Chun Zhang},
      title = {Nanowelding of carbon nanotube-metal contacts: An effective way to control the Schottky barrier and performance of carbon nanotube based field effect transistors},
      journal = {The Journal of Chemical Physics},
      publisher = {AIP},
      year = {2012},
      volume = {136},
      number = {17},
      pages = {174704},
      doi = {http://dx.doi.org/10.1063/1.4711082}
    }
    
    Anurag Srivastava, Arpit Jain, Rajnish Kurchania & Neha Tyagi Width Dependent Electronic Properties of Graphene Nanoribbons: An Ab-Initio Study 2012 Journal of Computational and Theoretical Nanoscience
    Vol. 9(7), 1008-1013 
    DOI  
    Abstract: We have analyzed the electronic properties of armchair and zigzag shaped graphene nanoribbons (GNRs) using density functional theory based ab-initio approach. The present computation employs the Perdew Zunger (PZ) type parameterized local density approximation (LDA) and revised Perdew Burke Ernzerhof (RPBE) type generalized gradient approximation (GGA) as exchange correlation functional. The calculated electronic band gap and density of states shows a close match with its other theoretical counterparts. In another observation, we have found a non linear variation of GNRs energy bandgap as a function of width.
    Keywords: graphene nanoribbons; dft; electronic properties; energy band gap; ATK; Application
    Area: graphene
    BibTeX:
    @article{Srivastava2012,
      author = {Srivastava, Anurag and Jain, Arpit and Kurchania, Rajnish and Tyagi, Neha},
      title = {Width Dependent Electronic Properties of Graphene Nanoribbons: An Ab-Initio Study},
      journal = {Journal of Computational and Theoretical Nanoscience},
      year = {2012},
      volume = {9},
      number = {7},
      pages = {1008--1013},
      doi = {http://dx.doi.org/10.1166/jctn.2012.2133}
    }
    
    Anurag Srivastava & Neha Tyagi Pressure induced zincblende to rocksalt phase transition in AlN nanocrystal 2012 Journal of Physics: Conference Series
    Vol. 377(1), 012066 
    DOI  
    Abstract: Structural phase transition in Aluminium nitride (AlN) nanocrystal has been studied within the framework of density-functional theory, using both the local-density as well as generalized gradient approximation as exchange correlation functionals. The study observes that under the application of pressure AlN nanocrystal transforms from its original zincblende (B3) type phase to hypothetical rocksalt (B1) type phase within the pressure range of 46 GPa to 56 GPa, which is comparatively larger than its bulk counterpart. The lattice parameter, bulk modulus and pressure derivatives of AlN nanocrystal in its original B3 type phase as well as hypothetical B1 type phase have also been computed as ground state properties. The mechanical strength of the AlN nanocrystal has been analysed in terms of volume collapse at transition pressure and bulk modulus.
    Keywords: ATK; Application; nanocrystal; phase transition;
    Area: semi
    BibTeX:
    @article{Srivastava2012a,
      author = {Anurag Srivastava and Neha Tyagi},
      title = {Pressure induced zincblende to rocksalt phase transition in AlN nanocrystal},
      journal = {Journal of Physics: Conference Series},
      year = {2012},
      volume = {377},
      number = {1},
      pages = {012066},
      doi = {http://dx.doi.org/10.1088/1742-6596/377/1/012066}
    }
    
    Anurag Srivastava & Neha Tyagi Pressure-induced phase transition in Ga1-xInxAs: ab initio study 2012 High Pressure Research
    Vol. 32(2)High Pressure Research, 299-308 
    DOI  
    Abstract: The high pressure phase transitions in Ga 1-x In x As (x=0.25, 0.5 and 0.75) alloys have been investigated using the ab initio density functional theory approach. The total energies and ground state properties have been analyzed using both the local density as well as generalized gradient approximations as exchange-correlation functionals. The study computes the structural phase transition in Ga 1-x In x As from its most stable zinc-blende- (B3) type phase to hypothetical rocksalt- (B1) type phase in the pressure range of 3-14 GPa. The observed transition pressures for the host binary compounds are in close agreement with their experimental/theoretical counterparts. The effect of introduction of indium in GaAs has also been analyzed on the lattice parameter, bulk modulus and transition pressure.
    Keywords: ab initio; phase transition; high pressure; alloys; III-V zincblende semiconductors; absorption fine-structure; random solid-solutions; electronic-structure; vibrational properties; molecular-dynamics; ATK; Application
    Area: semi
    BibTeX:
    @article{Srivastava2012b,
      author = {Srivastava, Anurag and Tyagi, Neha},
      title = {Pressure-induced phase transition in Ga1-xInxAs: ab initio study},
      booktitle = {High Pressure Research},
      journal = {High Pressure Research},
      publisher = {Taylor & Francis},
      year = {2012},
      volume = {32},
      number = {2},
      pages = {299--308},
      doi = {http://dx.doi.org/10.1080/08957959.2012.686613}
    }
    
    G.P. Tang, J.C. Zhou, Z.H. Zhang, X.Q. Deng & Z.Q. Fan Altering regularities of electronic transport properties in twisted graphene nanoribbons 2012 Applied Physics Letters
    Vol. 101(2), 023104 
    DOI  
    Abstract: Based on density-function theory combined with nonequilibrium Green's function method, the electronic transport properties of twisted armchair- and zigzag-edge graphene nanoribbons (AGNRs and ZGNRs) are investigated. Results show that electronic transport properties are sensitive to twisting deformations for semiconductor-type AGNRs, but are robust against twisting deformations for quasi-metallic AGNRs and ZGNRs. The electronic conduction becomes weaker gradually for moderate-gap semiconductor-type AGNRs, but gets stronger for wide-gap semiconductor-type AGNRs when the twisted angle increases to 120°. While for quasi-metallic AGNRs and ZGNRs, the electronic conduction is strong and obeys Ohm's law of resistance strictly. Mechanisms for such results are suggested.
    Keywords: density functional theory; electrical conductivity; graphene; Green's function methods; nanoribbons; wide band gap semiconductors; ATK; Application
    Area: graphene
    BibTeX:
    @article{Tang2012,
      author = {G. P. Tang and J. C. Zhou and Z. H. Zhang and X. Q. Deng and Z. Q. Fan},
      title = {Altering regularities of electronic transport properties in twisted graphene nanoribbons},
      journal = {Applied Physics Letters},
      publisher = {AIP},
      year = {2012},
      volume = {101},
      number = {2},
      pages = {023104},
      doi = {http://dx.doi.org/10.1063/1.4733618}
    }
    
    Yuta Tsuji, Aleksandar Staykov & Kazunari Yoshizawa Orbital Determining Spintronic Properties of a pi-Conjugated System 2012 J. Phys. Chem. C
    Vol. 116(30)The Journal of Physical Chemistry C, 16325-16332 
    DOI  
    Abstract: Spintronic properties of cyclobutadiene (CBD) systems are investigated based on a qualitative frontier orbital analysis. CBD undergoes a Jahn-Teller distortion from the square triplet state to the rectangular singlet state. According to the qualitative Hückel molecular orbital analysis, the electron transport through the square triplet state is symmetry allowed, whereas that through the rectangular singlet state is symmetry forbidden. The magnetic triplet state is a possible coexisting system of conductivity and magnetism. Sophisticated first-principles quantum chemical calculations are performed by using a realistic molecular junction model. Obtained results are in good agreement with the prediction based on the qualitative orbital analysis. Interesting spin filtering properties are found in the square-shaped CBD system. The high- and low-spin states of the square-shaped CBD system produce the spin-up and spin-down polarized conductance, respectively. The qualitative orbital analysis is useful as a guiding principle for designing molecular spintronics.
    Keywords: ATK; Application; molecular electronics; spin; spintronics; metal atom chains; electron-transport; cyclobutadiene dianion; magnetic-field; molecular wire; conductance; density; views; ring; hydrocarbons
    Area: molecular electronics; spin
    BibTeX:
    @article{Tsuji2012,
      author = {Tsuji, Yuta and Staykov, Aleksandar and Yoshizawa, Kazunari},
      title = {Orbital Determining Spintronic Properties of a pi-Conjugated System},
      booktitle = {The Journal of Physical Chemistry C},
      journal = {J. Phys. Chem. C},
      publisher = {American Chemical Society},
      year = {2012},
      volume = {116},
      number = {30},
      pages = {16325--16332},
      doi = {http://dx.doi.org/10.1021/jp305448q}
    }
    
    Cai-Juan Xia, De-Sheng Liu & Han-Chen Liu Phenylazoimidazole as a possible optical molecular switch: An ab initio study 2012 Optik - International Journal for Light and Electron Optics
    Vol. 123(14), 1307-1310 
    DOI URL 
    Abstract: By applying nonequilibrium Green's function formalism combined first-principles density functional theory, we investigate the electronic transport properties of the phenylazoimidazole optical molecular switch. The molecule that comprises the switch can convert between the cis and the trans forms upon photoexcitation. The influence of HOMO-LUMO gaps and the spatial distributions of molecular orbitals on the electronic transport through the molecular device are discussed in detail. Theoretical results show that the current through the trans form is significantly larger than through the cis form, which suggests this system has attractive potential application in future molecular switch technology.
    Keywords: Molecular switch; Nonequilibrium Green's function; Electronic transport; Density functional theory; ATK; Application; optical switch
    Area: molecular electronics
    BibTeX:
    @article{Xia2012d,
      author = {Xia, Cai-Juan and Liu, De-Sheng and Liu, Han-Chen},
      title = {Phenylazoimidazole as a possible optical molecular switch: An ab initio study},
      journal = {Optik - International Journal for Light and Electron Optics},
      year = {2012},
      volume = {123},
      number = {14},
      pages = {1307--1310},
      url = {http://www.sciencedirect.com/science/article/pii/S0030402611004554},
      doi = {http://dx.doi.org/10.1016/j.ijleo.2011.08.012}
    }
    
    Cai-Juan Xia, Ying-Tang Zhang & De-Sheng Liu Effect of torsion angle on the rectifying performance in the donor-bridge-acceptor single molecular device 2012 J. Theor. Comput. Chem.
    Vol. 11(04)Journal of Theoretical and Computational Chemistry, 735-743 
    DOI  
    Abstract: By applying nonequilibrium Green's function formalism combined with first-principles density functional theory, we investigate the effect of torsion angle on the rectifying performance in the donor-bridge-acceptor single molecular device. The influence of HOMO-LUMO gaps and the spatial distributions of molecular orbitals on the electronic transport through the molecular device are discussed in detail. The theoretical results show that the torsion angle plays an important role in the rectifying behavior of such devices. By changing the torsion angle, namely changing the magnitude of the intermolecular coupling effect, a different rectifying behavior can be observed in these systems. The results can provide fundamental guidelines for the design of functional molecular devices to a certain extent.
    Keywords: rectifying performance; nonequilibrium Green's function; electronic transport; density functional theory; electromechanical; conductance; switch; electronics; resistance; molecular electronics; ATK; Application;
    Area: molecular electronics
    BibTeX:
    @article{Xia2012e,
      author = {Xia, Cai-Juan and Zhang, Ying-Tang and Liu, De-Sheng},
      title = {Effect of torsion angle on the rectifying performance in the donor-bridge-acceptor single molecular device},
      booktitle = {Journal of Theoretical and Computational Chemistry},
      journal = {J. Theor. Comput. Chem.},
      publisher = {World Scientific Publishing Co.},
      year = {2012},
      volume = {11},
      number = {04},
      pages = {735--743},
      doi = {http://dx.doi.org/10.1142/S0219633612500496}
    }
    
    Fu-Qiu Ye, Zhi-Qiang Fan, Jun He, Jun Peng & Li-Ming Tang Theoretical investigation on current-voltage characteristics in all-carbon molecular device with different contact geometries 2012 Physica B: Condensed Matter
    Vol. 407(18), 3861-3864 
    DOI  
    Abstract: Applying nonequilibrium Green's functions in combination with the first-principles density-functional theory, we investigate electronic transport properties of an all-carbon molecular device consisting of one phenalenyl molecule and two zigzag graphene nanoribbons. The results show that the electronic transport properties are strongly dependent on the contact geometry and device's currents can drop obviously when the connect sites change from second-nearest sites from the central atom of the molecule (S site) to third-nearest sites from the central atom of the molecule (T site). More importantly, the negative differential resistance behavior is only observed on the negative bias region when the molecule connects the graphene nanoribbons through two T sites.
    Keywords: ATK; Application; nonequilibrium Green's functions; density-functional theory; molecular device; graphene; negative differential resistance behavior
    keywords plus: transport-properties; graphene; electrodes
    Area: graphene
    BibTeX:
    @article{Ye2012,
      author = {Ye, Fu-Qiu and Fan, Zhi-Qiang and He, Jun and Peng, Jun and Tang, Li-Ming},
      title = {Theoretical investigation on current-voltage characteristics in all-carbon molecular device with different contact geometries},
      journal = {Physica B: Condensed Matter},
      year = {2012},
      volume = {407},
      number = {18},
      pages = {3861--3864},
      doi = {http://dx.doi.org/10.1016/j.physb.2012.06.007}
    }
    
    H L Yu, X F Jiang, Y Zheng & G W Yang An ab initio study of MgO epitaxial layers on a Co 2 MnSi (0 0 1) surface: influence of the interface structure on tunnelling conductance 2012 Journal of Physics D: Applied Physics
    Vol. 45(32), 325002 
    DOI  
    Abstract: The formation of MgO epitaxial layers on a Co 2 MnSi (001) surface was studied using the ab initio electronic structure calculations based on the density functional theory. The free energy calculations showed that the O-rich, O-top and Mg-rich configurations in the CoCo termination case, and the O-rich and O-top configurations in the MnSi termination case were thermodynamically stable. The magnetic and electronic properties of these stable configurations were investigated in detail, and the results indicated that only the Mg-rich configuration with CoCo termination exhibited near half-metallic properties at the interface. The influence of the interfacial structure on the tunnelling conductance of the Co 2 MnSi/MgO/Co 2 MnSi magnetic tunnel junctions (MTJs) was also discussed using the nonequilibrium Green's function method. The attained conductance showed that a large difference of up to 10^4 was observed in the magnitude of parallel conductance, which means that the interface structure plays a crucial role in the electronic transport of the MTJ. These findings are useful in designing MTJs with high performance.
    Keywords: ATK; Application; MTJ; spin; FeMgO; magnetism; tunnel junction
    Area: interfaces; spin; nvm
    BibTeX:
    @article{Yu2012,
      author = {H L Yu and X F Jiang and Y Zheng and G W Yang},
      title = {An ab initio study of MgO epitaxial layers on a Co 2 MnSi (0 0 1) surface: influence of the interface structure on tunnelling conductance},
      journal = {Journal of Physics D: Applied Physics},
      year = {2012},
      volume = {45},
      number = {32},
      pages = {325002},
      doi = {http://dx.doi.org/10.1088/0022-3727/45/32/325002}
    }
    
    J.J. Zhang, Z.H. Zhang, C. Guo, J. Li & X.Q. Deng Electronic Transport Properties for a Zigzag-Edged Triangular Graphene 2012 Acta Physico-chimica Sinica
    Vol. 28(7), 1701-1706 
    DOI  
    Abstract: Based on the density functional theory and the non-equilibrium Green's function method, the electronic transport properties of zigzag-edged triangular graphene were studied systematically. The results revealed that the current voltage (I-V) characteristics and rectifying effects were closely related to the geometric size and the type of atoms terminated at the edges of triangular graphene. In the case of Hand S-terminated edges, a small triangular graphene had a large current but with a small rectifying ratio. Although the current increased, the rectifying behavior was lowered when H atoms at the edges of the structure were replaced by O atoms. Deeper analysis demonstrated that such a rectification was caused by the asymmetry in the spatial distribution of the frontier orbitals and an asymmetric movement on the molecular-level in triangular graphene under positive and negative biases. It is of great significance that our investigations develop a thorough understanding of the basic physical properties of a triangular graphene.
    Keywords: ATK; Application; nanoribbons; lattices; molecular electronics; graphene; triangular graphene; rectifying effect; electronic transport property; density functional theory; non-equilibrium Green's function method
    Area: graphene; molecular electronics
    BibTeX:
    @article{Zhang2012c,
      author = {Zhang, J. J. and Zhang, Z. H. and Guo, C. and Li, J. and Deng, X. Q.},
      title = {Electronic Transport Properties for a Zigzag-Edged Triangular Graphene},
      journal = {Acta Physico-chimica Sinica},
      publisher = {Peking Univ Press},
      year = {2012},
      volume = {28},
      number = {7},
      pages = {1701--1706},
      doi = {http://dx.doi.org/10.3866/PKU.WHXB201204172}
    }
    
    Hang Zhang, Jing Zeng & Ke-Qiu Chen Rectifying and negative differential resistance behaviors induced by asymmetric electrode coupling in Pyrene-based molecular device 2012 Physica E: Low-dimensional Systems and Nanostructures
    Vol. 44(7-8), 1631-1635 
    DOI  
    Abstract: By applying nonequilibrium Green's functions in combination with density-functional theory, we investigate the effect of asymmetric electrode coupling on electronic transport properties in a Pyrene-based molecular device. The results show that rectifying behaviors can be tuned by changing the coupling degree between Pyrene molecule and electrode. Moreover, negative differential resistance behavior can also be observed in this model. The mechanisms for these interesting phenomena are suggested.
    Keywords: junctions; conductance; transport; rectification; rectifiers; molecular electronics; ATK; Application
    Area: molecular electronics
    BibTeX:
    @article{Zhang2012d,
      author = {Zhang, Hang and Zeng, Jing and Chen, Ke-Qiu},
      title = {Rectifying and negative differential resistance behaviors induced by asymmetric electrode coupling in Pyrene-based molecular device},
      journal = {Physica E: Low-dimensional Systems and Nanostructures},
      year = {2012},
      volume = {44},
      number = {7-8},
      pages = {1631--1635},
      doi = {http://dx.doi.org/10.1016/j.physe.2012.04.008}
    }
    
    Peng Zhao & DeSheng Liu Electronic transport properties of capped-carbon-nanotube-based molecular junctions with multiple N and B dopants 2012 Chinese Science Bulletin
    Vol. 57, 2073-2077 
    DOI  
    Abstract: By applying non-equilibrium Green's function in combination with density functional theory, we investigated the electronic transport properties of capped-carbon-nanotube-based molecular junctions with multiple N and B dopants. The results show that the electronic transport properties are strongly dependent on the numbers and positions of N and B dopants. Best rectifying behavior is observed in the case with one N and one B dopants, and it is deteriorated strongly with the increasing dopants. The rectifying direction is even reversed with the change of doping positions. Moreover, obvious negative differential resistance behavior at very low bias is observed in some doping cases.
    Keywords: carbon nanotube; NDR; negative differential resistance; non-equilibrium Green's function; density functional theory; ATK; Application; dopants; boron; devices; circuits
    Area: nanotubes
    BibTeX:
    @article{Zhao2012g,
      author = {Zhao, Peng and Liu, DeSheng},
      title = {Electronic transport properties of capped-carbon-nanotube-based molecular junctions with multiple N and B dopants},
      journal = {Chinese Science Bulletin},
      publisher = {Science China Press, co-published with Springer},
      year = {2012},
      volume = {57},
      pages = {2073-2077},
      doi = {http://dx.doi.org/10.1007/s11434-012-5148-5}
    }
    
    Qing Zhao, Yang Wang, Jianjin Dong, Lina Zhao, X.F. Rui & Dapeng Yu Nanopore-Based DNA Analysis via Graphene Electrodes 2012 Journal of Nanomaterials
    Vol. 2012, 318950 
    DOI  
    Abstract: We propose an improvement for nanopore-based DNA analysis via transverse transport using graphene as transverse electrodes. Our simulation results show conspicuous distinction of tunneling current during translocation of different nucleotides through nanopore. Applying the single-atom thickness property of graphene, our findings demonstrate the feasibility of using graphene as transverse electrodes in future rapid and low-cost genome sequencing.
    Keywords: ATK; Application; graphene; DNA sequencing; sensor
    Area: graphene
    BibTeX:
    @article{Zhao2012h,
      author = {Qing Zhao and Yang Wang and Jianjin Dong and Lina Zhao and X. F. Rui and Dapeng Yu},
      title = {Nanopore-Based DNA Analysis via Graphene Electrodes},
      journal = {Journal of Nanomaterials},
      year = {2012},
      volume = {2012},
      pages = {318950},
      doi = {http://dx.doi.org/10.1155/2012/318950}
    }
    
    Ganhong Zheng, Zhenxiang Dai, Yanyan Zhang, Yuqin Dong, Yongqing Ma & Guang Li Molecular rectification of thiol-linked Au|PTCDI-[CH2]n|Au junctions 2012 Solid State Communications
    Vol. 152(16), 1535-1540 
    DOI  
    Abstract: The electronic transport properties of the PTCDI-[CH2]n (0<=n<=6) molecular junctions with different molecular lengths are theoretically investigated via the first-principles density functional theory (DFT) and non-equilibrium Green's function (NEGF) method. Our results show that the transport properties depend on molecular lengths. The equilibrium conductance of the probed systems decreases exponentially with the increasing number n of the CH2 unit. With n>=1, the rectifying effect has been found. In the n=6 case, a significant rectification ratio of 72.6 is achieved at the bias of ±2.1 V in our probed voltage range. The rectification effect arises from asymmetric molecular structures. Our results suggest these molecules have great potential application in the molecular-scale device.
    Keywords: ATK; Application; molecular electronics; electrical rectification; charge transport; rectifier; diimide; molecular lengths
    Area: molecular electronics
    BibTeX:
    @article{Zheng2012a,
      author = {Zheng, Ganhong and Dai, Zhenxiang and Zhang, Yanyan and Dong, Yuqin and Ma, Yongqing and Li, Guang},
      title = {Molecular rectification of thiol-linked Au|PTCDI-[CH2]n|Au junctions},
      journal = {Solid State Communications},
      year = {2012},
      volume = {152},
      number = {16},
      pages = {1535--1540},
      doi = {http://dx.doi.org/10.1016/j.ssc.2012.06.001}
    }
    
    Yan hong Zhou, Ling zhi Yuan & Xiao hong Zheng Ab initio study of the transport properties of a light-driven switching molecule azobenzene substituent 2012 Computational Materials Science
    Vol. 61(0), 145-149 
    DOI URL 
    Abstract: A first-principles computational approach is applied to study the transport properties of a light-sensitive molecular switch. The molecule of azobenzene substituent can convert between a trans and a cis configuration upon photoexcitation, which is the basis of the switch. The current-voltage (I-V) curves of the two configuration systems vary dramatically. The current across the cis configuration system is much bigger than that across the trans configuration in a rather wide applied bias window. The ON:OFF current ratio is bigger than 27 at the bias range [-1.3, -1.9] V and [1.6, 2.4] V and reaches 107 at the bias voltage -1.7 V. A detailed analysis of the projected density of states of the two configurations in the environment of two Al (100) nanoscale electrodes and the transmission spectra of the system reveals the mechanism of the switch.
    Keywords: Light-sensitive molecular switch; Projected density of states; First-principles; ATK; Application
    Area: molecular electronics
    BibTeX:
    @article{Zhou2012a,
      author = {Zhou, Yan-hong and Yuan, Ling-zhi and Zheng, Xiao-hong},
      title = {Ab initio study of the transport properties of a light-driven switching molecule azobenzene substituent},
      journal = {Computational Materials Science},
      year = {2012},
      volume = {61},
      number = {0},
      pages = {145--149},
      url = {http://www.sciencedirect.com/science/article/pii/S0927025612002388},
      doi = {http://dx.doi.org/10.1016/j.commatsci.2012.04.024}
    }
    
    Ruiping Zhou Structural And Electronic Properties of Two-Dimensional Silicene, Graphene, and Related Structures 2012 School: Wright State University, Electrical Engineering, Dayton, OH, USA  URL 
    Abstract: Traditional CMOS (complementary metal-oxide-semiconductor) transistors have already been in the nanometer range. As bulk silicon material is approaching its physical limits, it is highly desirable to seek novel, functional materials to continue Moore's law. Two-dimensional(2D) materials, such as graphene and silicene, have attracted great attention since they were envisioned a few years ago, having extraordinary electrical properties. Research in this work was focused on understanding the structural and electronic properties of a few atomic layers of carbon (graphene) and silicon (silicene). Atomic structures of the 2D materials, corresponding band structures, and transport properties were calculated based on density functional theory. Band gap was observed in AB forwardly-stacked bilayer silicene with proper layer distance. Applying an external electric field resulted in further opening of the band gap up to 0.19 eV. In addition, transmission spectrum and I-V curves were calculated. A new structure of a thin silicon layer on graphene substrate is proposed, showing different transport properties from 2D silicene.
    Keywords: ATK; Application; silicene; graphene
    Area: graphene; hexflats
    BibTeX:
    @mastersthesis{Zhou2012b,
      author = {Zhou, Ruiping},
      title = {Structural And Electronic Properties of Two-Dimensional Silicene, Graphene, and Related Structures},
      school = {Wright State University, Electrical Engineering, Dayton, OH, USA},
      year = {2012},
      url = {http://etd.ohiolink.edu/view.cgi/Zhou%20Ruiping.pdf?wright1341867892}
    }
    
    P.A. Gowri Sankar & K. Udhaya Kumar Mechanical and Electrical Properties of Single Walled Carbon Nanotubes: A Computational Study 2011 European Journal of Scientific Research
    Vol. 60(3), 324-340 
    URL 
    Abstract: Over the recent years, numerical modelling and computer based simulation of the properties of carbon nanotubes have become the focal points of research in computational nano-science. In this paper, we present the computational studies about the mechanical and transport properties of armchair (4, 4) and zigzag (4, 0) single walled carbon nanotubes (SWCNT). Unlike other materials, carbon nanotubes are so small that changes in structure can affect the Young's modulus. Young's modulus for an armchair single-wall carbon nanotube and zigzag single-wall carbon nanotube are calculated using an atomistic
    approach and density functional theory (DFT). Atomic forces and total energies for strained carbon nanotube segments are computed using Atomistix's Virtual NanoLab (VNL) and ToolKit (ATK) software. For a maximum strain of one percent, elastic moduli are calculated using both force-strain and energy-strain data. The average values found for Young's modulus are in the range 1.8 to 4.17 TPa depending on the cross-sectional area taken for the carbon nanotube and the calculation method used. This is in good agreement with recent experimental findings. By using ab initio density functional theory (DFT) and non-equilibrium green function approach (NEGF), the structural and electronic properties such as electronic band structure, density of states (DOS) and transmission spectrum of the single walled carbon nanotube (SWCNT) are investigated. The results suggest a wide range for practical applications, such as NEMS, acoustic sensors and nano actuators.
    Keywords: SWCNTs; DFT; NEGF; Young's modulus; band gap; nanotube; ATK; Application
    Area: nanotubes
    BibTeX:
    @article{Sankar2011,
      author = {P. A. Gowri Sankar and K. Udhaya Kumar},
      title = {Mechanical and Electrical Properties of Single Walled Carbon Nanotubes: A Computational Study},
      journal = {European Journal of Scientific Research},
      year = {2011},
      volume = {60},
      number = {3},
      pages = {324-340},
      url = {http://www.eurojournals.com/EJSR_60_3.htm}
    }
    
    Yingying Zhang, Feng-Chao Wang & Ya-Pu Zhao Negative differential resistance behavior of silicon monatomic chain encapsulated in carbon nanotubes 2012 Computational Materials Science
    Vol. 62(0), 87-92 
    DOI  
    Abstract: Using nonequilibrium Green's functions in combination with density-functional theory (DFT), we investigated the electronic transport properties of the silicon monatomic chains (SiMCs) with different geometries which were induced by the encapsulation of the carbon nanotubes (CNTs). The encapsulated SiMCs, which were put inside (5,5), (6,6), (7,7) and (8,8) hydrogenated armchair CNTs, were coupled to two Au (100) nanoscale electrodes. The electronic transport property of an isolated finite SiMC was also studied to serve as a reference to our calculations. As the diameter of CNTs increases, the geometry structures of SiMCs changed. Calculated results show that the current-voltage (I-V) characteristics depend sensitively on the geometry structures of SiMCs and can be controlled by the size-selective encapsulation. Negative differential resistance (NDR) phenomena were observed within certain bias voltage ranges. A detailed analysis of the origin of NDR was carried out with the transmission spectrum, the spatial distribution of frontier molecular orbitals and the molecular projected self-consistent Hamiltonian (MPSH) states taken into consideration. These results indicated that the size-selective encapsulation of SiMCs in CNTs can become a possible candidate for designing the silicon-based nanoelectronic devices.
    Keywords: field-effect transistors; nanowires; simulations; silicon monatomic chain; size-selective encapsulation; electronic transport properties; negative differential resistance; NDR; transmission spectrum; nanotubes; ATK; Application
    Area: nanotubes
    BibTeX:
    @article{Zhang2012b,
      author = {Zhang, Yingying and Wang, Feng-Chao and Zhao, Ya-Pu},
      title = {Negative differential resistance behavior of silicon monatomic chain encapsulated in carbon nanotubes},
      journal = {Computational Materials Science},
      year = {2012},
      volume = {62},
      number = {0},
      pages = {87--92},
      doi = {http://dx.doi.org/10.1016/j.commatsci.2012.04.050}
    }
    
    Kamal K. Saha, Anders Blom, Kristian S. Thygesen & Branislav K. Nikolic Magnetoresistance and negative differential resistance in Ni/graphene/Ni vertical heterostructures driven by finite bias voltage: A first-principles study 2012 Phys. Rev. B
    Vol. 85(18), 184426 
    DOI  
    Abstract: Using the nonequilibrium Green's function formalism combined with density functional theory, we study finite bias quantum transport in Ni/Gr[n]/Ni vertical heterostructures where n graphene layers are sandwiched between two semi-infinite Ni(111) electrodes. We find that the recently predicted "pessimistic" magnetoresistance of 100% for n>=5 junctions at zero bias voltage Vb->0 persists up to Vb~0.4 V, which makes such devices promising for spin-torque-based device applications. In addition, for parallel orientations of the Ni magnetizations, the n=5 junction exhibits a pronounced negative differential resistance as the bias voltage is increased from Vb=0 V to Vb~0.5 V. We confirm that both of these nonequilibrium transport effects hold for different types of bonding of Gr on the Ni(111) surface while maintaining Bernal stacking between individual Gr layers.
    Keywords: ATK; Application; graphene; magneto-tunnel resistance; TMR; Nickel surface; NDR; negative differential resistance; MTJ;
    Area: graphene; spin; nvm
    BibTeX:
    @article{Saha2012a,
      author = {Saha, Kamal K. and Blom, Anders and Thygesen, Kristian S. and Nikolic, Branislav K.},
      title = {Magnetoresistance and negative differential resistance in Ni/graphene/Ni vertical heterostructures driven by finite bias voltage: A first-principles study},
      journal = {Phys. Rev. B},
      publisher = {American Physical Society},
      year = {2012},
      volume = {85},
      number = {18},
      pages = {184426},
      doi = {http://dx.doi.org/10.1103/PhysRevB.85.184426}
    }
    
    Y.H. Chen, C.M. Zhang, J.B. Wu & Q. Lin Effect of O/N Substitutive Doping on the Band Structure and Transport Properties of the zigzag Boron Nitride Narrow-Nanoribbons 2012 Acta Physico-chimica Sinica
    Vol. 28(3), 567-572 
    DOI  
    Abstract: By performing first-principles calculations and non-equilibrium Green's function, the energy band structure, transmission spectrum and current voltage characteristics of the O-doping zigzag boron nitride narrow-nanoribbons (z-BNNNRs) were investigated. The calculation results show that O-doping remarkably changes the z-BNNNRs energy band structure and transform the material from a semiconductor to a metal. It is also demonstrated that the system exhibits an obvious negative differential resistance (NDR) characteristic. Further investigations revealed that the position and concentration of O-doping also affected the NOR behavior over a certain range of bias. The negative differential conductance (NDC) for edge-doping is greater than that for middle-doping and the maximum of the NDC increases with an increase of the concentration of O-doping. This special electronic transport property of O-doping z-BNNNRs makes it more suitable as a candidate for molecular devices.
    Keywords: BN nanoribbon; O-doping; energy band structure; transport property; negative differential resistance; NRD; armchair graphene nanoribbons; electronic-structure; ATK; Application
    Area: graphene
    BibTeX:
    @article{Chen2012,
      author = {Chen, Y. H. and Zhang, C. M. and Wu, J. B. and Lin, Q.},
      title = {Effect of O/N Substitutive Doping on the Band Structure and Transport Properties of the zigzag Boron Nitride Narrow-Nanoribbons},
      journal = {Acta Physico-chimica Sinica},
      year = {2012},
      volume = {28},
      number = {3},
      pages = {567--572},
      doi = {http://dx.doi.org/10.3866/PKU.WHXB201112071}
    }
    
    P.J. Mohan, V.P. Georgiev & J.E. McGrady Periodic trends in electron transport through extended metal atom chains: comparison of Ru-3(dpa)(4)(NCS)(2) with its first-row analogues 2012 Chemical Science
    Vol. 3(4), 1319-1329 
    DOI  
    Abstract: Density functional theory is used to reconcile the structural, magnetic and electron transport properties of a triruthenium extended metal atom chain, Ru-3(dpa)(4)(NCS)(2). The distinct bending of the Ru-Ru-Ru core in this species is traced to strong second-order mixing between levels of sigma and pi symmetry that are near degenerate in the linear geometry. The dominant electron transport channel is formed by the LUMO, an orbital of pi* symmetry that lies just above the Fermi level of the gold electrode. The bending has a substantial impact on electron transport in that it induces a spin crossover from a quintet to a singlet which in turn brings the LUMO much closer to the Fermi level. The presence of significant net pi bonding in the metal chains also broadens the pi/pi(nb)/pi* manifold, such that the channel is not strongly perturbed by the electric field, even at a bias of 1.0 V. The presence of a robust pi symmetry conduction channel marks the triruthenium systems out as quite distinct from its first-row counterparts, Cr-3(dpa)(4)(NCS)(2) and Co-3(dpa)(4)(NCS)(2), where current flows primarily through the sigma framework.
    Keywords: bond-stretch isomerism; regular 2-component Hamiltonians; linear trimetallic complexes; molecular wire; transition-metal; string complexes; carbon nanotubes; ab-initio; electrochemical properties; magnetic-properties; ATK; Application; spin
    Area: molecular electronics; spin
    BibTeX:
    @article{Mohan2012,
      author = {Mohan, P. J. and Georgiev, V. P. and McGrady, J. E.},
      title = {Periodic trends in electron transport through extended metal atom chains: comparison of Ru-3(dpa)(4)(NCS)(2) with its first-row analogues},
      journal = {Chemical Science},
      year = {2012},
      volume = {3},
      number = {4},
      pages = {1319--1329},
      doi = {http://dx.doi.org/10.1039/c2sc01024k}
    }
    
    Cai-Juan Xia, Han Chen Liu & Ying Tang Zhang Theory of the Rectifying Performance in Molecular Device: The Role of Anchoring Groups 2012 Solid State Phenomena
    Vol. 181-182, 344-347 
    DOI  
    Abstract: The electronic transport of the single molecule via different anchoring groups is studied using density functional theory in conjunction with the nonequilibrium Green's function. The results show that the electronic transport properties are strongly dependent on the anchoring groups. Asymmetric electrical response for opposite biases is observed resulting in significant rectification in current. The transmission coefficients and spatial distributions of molecular orbitals under various external biases voltage are analyzed, and it suggests that the asymmetry of the coupling between the molecule and the electrodes with external bias leads to rectifying performance.
    Keywords: anchoring groups; density functional theory (DFT); electronic transport; nonequilibrium Green's function; rectification; ATK; Application
    Area: molecular electronics
    BibTeX:
    @article{Xia2012b,
      author = {Cai-Juan Xia and Han Chen Liu and Ying Tang Zhang},
      title = {Theory of the Rectifying Performance in Molecular Device: The Role of Anchoring Groups},
      journal = {Solid State Phenomena},
      year = {2012},
      volume = {181-182},
      pages = {344-347},
      doi = {http://dx.doi.org/10.4028/www.scientific.net/SSP.181-182.344}
    }
    
    Cai-Juan Xia, Ying Tang Zhang & Xue Jun Zai Negative Differential Resistance Induced by Intermolecular Interaction in Molecular Device 2012 Solid State Phenomena
    Vol. 181-182, 312-315 
    DOI  
    Abstract: Based on nonequilibrium Green's function and first-principles calculation, we investigate the transport properties of the molecule device with a donor-acceptor molecular complex sandwiched between two electrodes. Numerical results show that a negative differential resistance under applied bias can be observed. The mechanism of negative differential resistance is mainly induced by the orbital match of molecule and electrodes as well as intermolecular charge transfer.
    Keywords: density functional theory (DFT); electronic transport; negative differential resistance; NDR; non-equilibrium Green's function; ATK; Application
    Area: molecular electronics
    BibTeX:
    @article{Xia2012c,
      author = {Cai-Juan Xia and Ying Tang Zhang and Xue Jun Zai},
      title = {Negative Differential Resistance Induced by Intermolecular Interaction in Molecular Device},
      journal = {Solid State Phenomena},
      year = {2012},
      volume = {181-182},
      pages = {312-315},
      doi = {http://dx.doi.org/10.4028/www.scientific.net/SSP.181-182.312}
    }
    
    H.P. Xiao, Zhizhou Yu, M.L. Hu, X.Y. Peng, L.Z. Sun & Jianxin Zhong Zigzag graphene nanoribbons: Flexible and robust transparent conductors 2012 Solid State Sciences
    Vol. 14(6), 711-714 
    DOI  
    Abstract: We report the effect of bending deformation on the optical and transport properties of zigzag graphene nanoribbons (ZGNRs) induced by the uniaxial strain using the first-principles method combined with non-equilibrium Green's function. The optical properties of ZGNRs in the region of visible light are almost unchanged under the uniaxial strain, whereas an absorption peak occurs at the infrared region for the bent ZGNRs under the transverses strain. The transport properties of ZGNRs under the transverses strain with the bending angle up to 65 degrees remain almost the same as those of the flat one. The transmission coefficients around the Fermi level only slightly decrease when the bending angle further increases to 72.5 degrees. Moreover, ZGNRs under the longitudinal strain show the same transmission conductance around the Fermi level as that of the flat one. The edge states of ZGNRs still behave as excellent ballistic transport channels under bending deformation, which makes them promising flexible and robust transparent conductors.
    Keywords: total-energy calculations; carbon nanotube films; wave basis-set; semiconductors; oxide; form; graphene nanoribbon; bending deformation; optical property; transport property; ATK; Application
    Area: graphene
    BibTeX:
    @article{Xiao2012,
      author = {Xiao, H.P. and Yu, Zhizhou and Hu, M.L. and Peng, X.Y. and Sun, L.Z. and Zhong, Jianxin},
      title = {Zigzag graphene nanoribbons: Flexible and robust transparent conductors},
      journal = {Solid State Sciences},
      year = {2012},
      volume = {14},
      number = {6},
      pages = {711--714},
      doi = {http://dx.doi.org/10.1016/j.solidstatesciences.2012.03.027}
    }
    
    Zhi-Qiang Fan & Xie Fang Effect of B and N doping on the negative differential resistance in molecular device 2012 Acta Phys. Sin.
    Vol. 61(7), 077303 
    URL 
    Abstract: By using nonequilibrium Green's functions in combination with the density-functional theory, we investigate the effects of B and N doping on the transport properties in phenalenyl molecular device. The calculated results show that negative differential resistance behavior can be observed in phenalenyl molecular device where the device current can decrease with the base voltage increasing particularly in a bias voltage region, and the peak-to-valley current ratio reaches up to 5.12. The device current can be increased before 0.8 V when the molecular center atom is replaced by B or N atom. But, the negative differential resistance behavior can be weakened and the peak-to-valley current ratio can decrease to 3.83 and 3.61, respectively. The doping effects of B and N, which are induced by the difference in extranuclear electron number between them, can make the orbitals and corresponding transmission peaks move toward high or low energy to modulate the electronic transport ability and the negative differential resistance behavior of the device.
    Keywords: ATK; Application; molecular electronics; doping; nonequilibrium Green's functions; density-functional theory; electronic transport; negative differential resistance behavior;
    Area: molecular electronics
    BibTeX:
    @article{Fan2012a,
      author = {Fan, Zhi-Qiang and Xie Fang},
      title = {Effect of B and N doping on the negative differential resistance in molecular device},
      journal = {Acta Phys. Sin.},
      year = {2012},
      volume = {61},
      number = {7},
      pages = {077303},
      url = {http://wulixb.iphy.ac.cn/EN/abstract/abstract47220.shtml}
    }
    
    Jun He, Ke-Qiu Chen & Chang Q. Sun The weak pi-pi interaction originated resonant tunneling and fast switching in the carbon based electronic devices 2012 AIP Advances
    Vol. 2(1), 012137 
    DOI  
    Keywords: density functional theory; fullerene devices; fullerenes; Green's function methods; negative resistance; resonant tunnelling; ATK; Application
    Area: fullerenes
    BibTeX:
    @article{He2012a,
      author = {Jun He and Ke-Qiu Chen and Chang Q. Sun},
      title = {The weak pi-pi interaction originated resonant tunneling and fast switching in the carbon based electronic devices},
      journal = {AIP Advances},
      publisher = {AIP},
      year = {2012},
      volume = {2},
      number = {1},
      pages = {012137},
      doi = {http://dx.doi.org/10.1063/1.3685777}
    }
    
    Kenji Toyoda Theoretical Investigation of Chemical Spin Doping into Single Porphyrin Junctions toward Ultrahigh-Sensitive Nitric Oxide Sensor 2012 Japanese Journal of Applied Physics
    Vol. 51(4), 045202 
    DOI  
    Abstract: We theoretically study chemical spin doping into single porphyrins connected to nanoelectrodes via benzenethiols, ethynyl-benzenethiols, and vinyl-benzenethiols using the adsorption of a nitric oxide (NO) molecule. For all three anchoring groups, the adsorption of a NO molecule injects one spin into single-molecule junctions and produces antiferromagnetic interactions between the injected spin and the original spins at the junctions, resulting in a decrease in the spin-polarized currents. We found that the magnitude of change in the spin-polarized current significantly depends on the type of anchoring groups; the magnitude is ordered by the following anchoring group: vinyl-benzenethiol > ethynyl-benzenethiol > benzenethiol. In particular, for vinyl-benzenethiol, spin doping causes not only pi electron localization on molecular orbitals but also structural change.
    Keywords: ATK; Application; sensor; molecular electronics; molecular spintronics; transport properties; conductance; devices; wires
    Area: molecular electronics; spin
    BibTeX:
    @article{Toyoda2012,
      author = {Toyoda, Kenji},
      title = {Theoretical Investigation of Chemical Spin Doping into Single Porphyrin Junctions toward Ultrahigh-Sensitive Nitric Oxide Sensor},
      journal = {Japanese Journal of Applied Physics},
      year = {2012},
      volume = {51},
      number = {4},
      pages = {045202},
      doi = {http://dx.doi.org/10.1143/JJAP.51.045202}
    }
    
    Cai-Juan Xia, De-Sheng Liu, De-Hua Zhang & Han-Chen Liu Theoretical Studies of the Rectifying Performance In Diblock Molecular Junctions: the Role of the Anchoring Groups 2012 International Journal of Modern Physics B
    Vol. 26(11), 1250082 
    DOI  
    Abstract: By applying nonequilibrium Green's function formalism combined with first-principles density functional theory, we investigate the effect of different anchoring groups on the rectifying behavior in diblock molecular junctions. The spatial distributions of molecular orbitals and the influence of transmission coefficients under various external voltage biases on the electronic transport through the molecular device are discussed in detail. The results show that the anchoring groups play a significant role on the electronic transport properties. The rectifying performance in molecular junctions can be manipulated, enhanced, or suppressed by a careful consideration of the effects of the anchoring group and such modifications become crucial in optimizing the electronic transport properties of chemical structures.
    Keywords: ATK; Application; molecular electronics; rectifying performance; nonequilibrium green's function; electronic transport; density functional theory; single-molecule; conductance; switch; electronics; diodes
    Area: molecular electronics
    BibTeX:
    @article{Xia2012a,
      author = {Xia, Cai-Juan and Liu, De-Sheng and Zhang, De-Hua and Liu, Han-Chen},
      title = {Theoretical Studies of the Rectifying Performance In Diblock Molecular Junctions: the Role of the Anchoring Groups},
      journal = {International Journal of Modern Physics B},
      year = {2012},
      volume = {26},
      number = {11},
      pages = {1250082},
      doi = {http://dx.doi.org/10.1142/S0217979212500828}
    }
    
    Z.Q. Bai, Y.H. Lu, L. Shen, V. Ko, G.C. Han & Y.P. Feng Transport properties of high-performance all-Heusler Co2CrSi/Cu2CrAl/Co2CrSi giant magnetoresistance device 2012 Journal of Applied Physics
    Vol. 111(9), 093911 
    DOI  
    Abstract: Transport properties of giant magnetoresistance (MR) junction consisting of trilayer Co2CrSi/Cu2CrAl/Co2CrSi Heusler alloys (L21) are studied using first-principles approach based on density functional theory and the non-equilibrium Green's function method. Highly conductive channels are found in almost the entire k-plane when the magnetizations of the electrodes are parallel, while they are completely blocked in the antiparallel configuration, which leads to a high magnetoresistance ratio (the pessimistic MR ratio is nearly 100%). Furthermore, the calculated I-V curve shows that the device behaves as a good spin valve with a considerable disparity in currents under the parallel and antiparallel magnetic configurations of the electrodes. The Co2CrSi/Cu2CrAl/Co2CrSi junction could be useful for high-performance all-metallic current-perpendicular-to-plane giant magnetoresistance reading head for the next generation high density magnetic storage.
    Keywords: ab initio calculations; aluminium alloys; chromium alloys; cobalt alloys; copper alloys; density functional theory; electrodes; giant magnetoresistance; Green's function methods; magnetic storage; silicon alloys; spin valves; ATK; Application; spin; MTJ
    Area: interfaces; spin; nvm
    BibTeX:
    @article{Bai2012a,
      author = {Z. Q. Bai and Y. H. Lu and L. Shen and V. Ko and G. C. Han and Y. P. Feng},
      title = {Transport properties of high-performance all-Heusler Co2CrSi/Cu2CrAl/Co2CrSi giant magnetoresistance device},
      journal = {Journal of Applied Physics},
      publisher = {AIP},
      year = {2012},
      volume = {111},
      number = {9},
      pages = {093911},
      doi = {http://dx.doi.org/10.1063/1.4712301}
    }
    
    Sun Young Baik, Yong Jae Cho, Young Rok Lim, Hyung Soon Im, Dong Myung Jang, Yoon Myung, Jeunghee Park & Hong Seok Kang Charge-Selective Surface-Enhanced Raman Scattering Using Silver and Gold Nanoparticles Deposited on Silicon-Carbon Core-Shell Nanowires 2012 ACS Nano
    Vol. 6(3)ACS Nano, 2459-2470 
    DOI  
    Abstract: The deposition of silver (Ag) or gold (Au) nanoparticles (NPs) on vertically aligned silicon-carbon (Si-C) core-shell nanowires (NWs) produces sensitive substrates for surface-enhanced Raman spectroscopy (SERS). The undoped and 30% nitrogen (N)-doped graphitic layers of the C shell (avg thickness of 20 nm) induce a higher sensitivity toward negatively (-) and positively (+) charged dye molecules, respectively, showing remarkable charge selectivity. The Ag NPs exhibit higher charge selectivity than the Au NPs. The Ag NPs deposited on p- and n-type Si NWs also exhibit (-) and (+) charge selectivity, respectively, which is higher than that of the Au NPs. The X-ray photoelectron spectroscopy analysis indicates that the N-doped graphitic layers donate more electrons to the metal NPs than the undoped ones. More distinct electron transfer occurs to the Ag NPs than to the Au NPs. First principles calculations of the graphene-metal adducts suggest that the large electron transfer capacity of the N-doped graphitic layers is due to the formation of a N->Ag coordinate bond involving the lone pair electrons of the N atoms. We propose that the more (-) charged NPs on the N-doped graphitic layers prefer the adsorption of (+) charged dyes, enhancing the SERS intensity. The charge selectivity of the Si NW substrates can also be rationalized by the greater electron transfer from the n-type Si to the metal NPs.
    Keywords: ATK; Application; surface-enhanced Raman scattering; charge selectivity; N-doped graphitic layers; silicon nanowires; silver nanoparticles; first principles calculations; electron transfer
    Area: nanowires
    BibTeX:
    @article{Baik2012,
      author = {Baik, Sun Young and Cho, Yong Jae and Lim, Young Rok and Im, Hyung Soon and Jang, Dong Myung and Myung, Yoon and Park, Jeunghee and Kang, Hong Seok},
      title = {Charge-Selective Surface-Enhanced Raman Scattering Using Silver and Gold Nanoparticles Deposited on Silicon-Carbon Core-Shell Nanowires},
      booktitle = {ACS Nano},
      journal = {ACS Nano},
      publisher = {American Chemical Society},
      year = {2012},
      volume = {6},
      number = {3},
      pages = {2459--2470},
      doi = {http://dx.doi.org/10.1021/nn204797b}
    }
    
    Chang-Jie Dai, Xiao-Hong Yan, Yan-Dong Guo & Yang Xiao Effect of an out-of-plane cross connection on the electronic transport of zigzag graphene nanoribbon 2012 Physics Letters A
    Vol. 376(26-27), 2010-2014 
    DOI  
    Abstract: Electronic transport properties of out-of-plane graphene nanoribbon intersections have been investigated by using computational method. The inter-distance between two graphene nanoribbons is found to affect the transport properties strongly and its affection can be neglected for larger ones, even under an external bias. Wider graphene nanoribbons will bring stronger interaction into the system, and result in more transmission dips. Moreover, the stacking configuration between two graphene nanoribbons is found to be crucial for the electronic transport under an external bias, as it can affect the electronic transport strongly near the charge neutral point.
    Keywords: graphene nanoribbon; cross connection; electronic transport; ATK; Application
    Area: graphene
    BibTeX:
    @article{Dai2012,
      author = {Dai, Chang-Jie and Yan, Xiao-Hong and Guo, Yan-Dong and Xiao, Yang},
      title = {Effect of an out-of-plane cross connection on the electronic transport of zigzag graphene nanoribbon},
      journal = {Physics Letters A},
      year = {2012},
      volume = {376},
      number = {26-27},
      pages = {2010--2014},
      doi = {http://dx.doi.org/10.1016/j.physleta.2012.04.054}
    }
    
    Xiaoqing Deng, Guiping Tang & Chao Guo Tuning the electronic transport properties for a trigonal graphene flake 2012 Physics Letters A
    Vol. 376(23), 1839-1844 
    DOI URL 
    Abstract: By applying nonequilibrium Green's functions in combination with density-functional theory, we have investigated the effects of two side groups, NH2 and NO2, on the electronic transport properties of the trigonal graphene flake. It has been found that the rectifying ratios (RR) and direction can be significantly tuned by the type and the attached positions of side groups. The NH2 group shows an obvious electron-donating characteristic, whereas NO2 group demonstrates a poorly electron-accepting behavior in these systems. The analysis on the spatial distribution and the energy level of frontier orbitals, transmission spectra, and electrostatic potential distribution give an inside view of the observed results.
    Keywords: Electronic transport; Graphene quantum dot; Density-functional theory; ATK; Application
    Area: graphene
    BibTeX:
    @article{Deng2012a,
      author = {Deng, Xiaoqing and Tang, Guiping and Guo, Chao},
      title = {Tuning the electronic transport properties for a trigonal graphene flake},
      journal = {Physics Letters A},
      year = {2012},
      volume = {376},
      number = {23},
      pages = {1839--1844},
      url = {http://www.sciencedirect.com/science/article/pii/S0375960112004665},
      doi = {http://dx.doi.org/10.1016/j.physleta.2012.04.021}
    }
    
    Neeraj K. Jaiswal & Pankaj Srivastava Ab-Initio Study of Transition Metal (Ni) Interaction with Zigzag Graphene Nanoribbons 2012 Journal of Computational and Theoretical Nanoscience
    Vol. 9(4), 555-559 
    DOI  
    Abstract: We have performed a systematic study to investigate how transition metal (TM) atoms affect the electronic properties of zigzag graphene nanoribbons (ZGNR). We considered the interaction of ZGNR and TM taking Ni as a terminating element as well as a substitutional dopant at single vacancy sites. Present calculations revealed that all the considered ribbons have ferromagnetic ground state. The calculated binding energy varies from -6.86 eV to -10.55 eV for Ni-termination and -4.07 eV to -10.35 eV for Ni-doping that shows a rather strong binding. The present calculations revealed that edge doped ribbons are energetically more favourable than the center doping. Ni-termination enhances the metallicity with a little distortion in the characteristics band structure of ZGNR whereas in Ni-doping, the characteristics band structure is lost and a dispersive band appears at Fermi level. The position of this dispersive band is independent of the ribbon width and thus equalizing the metallicity in ZGNR. Width independent metallicity is crucial at nano regime.
    Keywords: graphene nanoribbon; ATK; Application; binding energy; electronic band structure; spin
    Area: graphene; spin
    BibTeX:
    @article{Jaiswal2012,
      author = {Jaiswal, Neeraj K. and Srivastava, Pankaj},
      title = {Ab-Initio Study of Transition Metal (Ni) Interaction with Zigzag Graphene Nanoribbons},
      journal = {Journal of Computational and Theoretical Nanoscience},
      year = {2012},
      volume = {9},
      number = {4},
      pages = {555-559},
      doi = {http://dx.doi.org/10.1166/jctn.2012.2060}
    }
    
    Xinqian Li, Aleksandar Staykov & Kazunari Yoshizawa Orbital Views on Electron-Transport Properties of Cyclophanes: Insight into Intermolecular Transport: 2012 Bulletin of the Chemical Society of Japan
    Vol. 85(2), 181-188 
    DOI  
    Abstract: Electron-transport properties of cyclophanes are investigated with qualitative Hückel molecular orbital analysis for better understanding of the intermolecular interaction in molecular devices. Charge and electron transfers often take place via through-space interactions, which are observed both in large biological molecules and in organic molecular crystals. Since the intermolecular electronic coupling in pi-stacked structures plays an important role in total device performance, in this work [2,2]paracyclophane is studied to investigate the effect of the intermolecular interactions in aromatic hydrocarbons on its electron-transport properties. According to the orbital symmetry rule, the symmetry-allowed and symmetry-forbidden connections for electron transport between the benzene rings are predicted just from the phase and amplitude of the frontier orbitals. The meta connection is symmetry allowed for electron transport while the para and ortho connections are symmetry forbidden. The qualitative predictions made with the Hückel approximation are found consistent with the calculation results obtained with density functional theory. The qualitative but essential understanding in the orbital views would extend the application of the rule from a single molecule to a crystal structure for the development of high-performance molecular devices.
    Keywords: ATK-SE; Application; molecular electronics; orbital view;
    Area: molecular electronics
    BibTeX:
    @article{Li2012d,
      author = {Li, Xinqian and Staykov, Aleksandar and Yoshizawa, Kazunari},
      title = {Orbital Views on Electron-Transport Properties of Cyclophanes: Insight into Intermolecular Transport: },
      journal = {Bulletin of the Chemical Society of Japan},
      year = {2012},
      volume = {85},
      number = {2},
      pages = {181--188},
      doi = {http://dx.doi.org/10.1246/bcsj.20110256}
    }
    
    Ming-Jun Li, Hui Xu, Ke-Qiu Chen & Meng-Qiu Long Electronic transport properties in benzene-based heterostructure: Effects of anchoring groups 2012 Physics Letters A
    Vol. 376(20), 1692-1697 
    DOI  
    Abstract: Using density functional theory (DFT) combined with nonequilibrium Green's functions (NEGF), the electronic transport properties of benzene-based heterostructure molecular devices have been investigated. We focus on the contact geometry between molecules and electrodes, and several different anchoring groups have been considered. The current-voltage characteristics were calculated for positive and negative bias voltages, and discussed in terms of transmission spectra, transferred charges, and molecular projected self-consistent Hamiltonian (MPSH) states. Our results show that the anchoring groups play a crucial role in determining the overall conductivity of the molecular devices. Negative differential resistance (NDR) and rectifying effect can be observed.
    Keywords: anchoring group; transport property; rectifying effect; NDR behavior; molecular junctions; room-temperature; carbon nanotube; conductance; devices; 1st-principles; rectification; transistors; rectifiers; film; negative differential resistance; ATK; Application
    Area: molecular electronics
    BibTeX:
    @article{Li2012e,
      author = {Li, Ming-Jun and Xu, Hui and Chen, Ke-Qiu and Long, Meng-Qiu},
      title = {Electronic transport properties in benzene-based heterostructure: Effects of anchoring groups},
      journal = {Physics Letters A},
      year = {2012},
      volume = {376},
      number = {20},
      pages = {1692--1697},
      doi = {http://dx.doi.org/10.1016/j.physleta.2012.03.061}
    }
    
    Yong-Jun Li, Qing-Qing Sun, Lin Chen, Peng Zhou, Peng-Fei Wang, Shi-Jin Ding & David Wei Zhang Hexagonal boron nitride intercalated multi-layer graphene: a possible ultimate solution to ultra-scaled interconnect technology 2012 AIP Advances
    Vol. 2(1), 012191 
    DOI  
    Abstract: We proposed intercalation of hexagonal boron nitride (hBN) in multilayer graphene to improve its performance in ultra-scaled interconnects for integrated circuit. The effect of intercalated hBN layer in bilayer graphene is investigated using non-equilibrium Green's functions. We find the hBN intercalated bilayer graphene exhibit enhanced transport properties compared with pristine bilayer ones, and the improvement is attributed to suppression of interlayer scattering and good planar bonding condition of inbetween hBN layer. Based on these results, we proposed a via structure that not only benefits from suppressed interlayer scattering between multilayer graphene, but also sustains the unique electrical properties of graphene when many graphene layers are stacking together. The ideal current density across the structure can be as high as 4.6×10^9 A/cm^2 at 1 V, which is very promising for the future high-performance interconnect.
    Keywords: boron compounds; current density; electrical conductivity; graphene; Green's function methods; III-V semiconductors; intercalation compounds; multilayers; semiconductor-insulator boundaries; wide band gap semiconductors ; ATK; Application
    Area: graphene
    BibTeX:
    @article{Li2012f,
      author = {Li, Yong-Jun and Sun, Qing-Qing and Chen, Lin and Zhou, Peng and Wang, Peng-Fei and Ding, Shi-Jin and Zhang, David Wei},
      title = {Hexagonal boron nitride intercalated multi-layer graphene: a possible ultimate solution to ultra-scaled interconnect technology},
      journal = {AIP Advances},
      publisher = {AIP},
      year = {2012},
      volume = {2},
      number = {1},
      pages = {012191},
      doi = {http://dx.doi.org/10.1063/1.3701267}
    }
    
    Wenhu Liao, Heping Zhao, Gang Ouyang, Ke-Qiu Chen & Guanghui Zhou Symmetry of atomistic structure for armchair-edge graphene nanoribbons under uniaxial strain 2012 Applied Physics Letters
    Vol. 100(15), 153112 
    DOI  
    Abstract: We present a systematic first-principles calculation on the atomistic structural variation for armchair-edge graphene nanoribbons (AGNRs) under a small planar uniaxial strain along armchair and zigzag directions, respectively. Interestingly, it is found that asymmetric AGNRs are more sensitive to the external strain with more types of carbon-carbon bonds and angles, while symmetric ones show less types of bonds and angles under the same strain. This difference is attributed to the symmetric property of AGNRs combining with the bond theory. Our findings may be useful in further understanding of GNRs under strain and in designing nanoelectromechanical devices based on GNRs.
    Keywords: ab initio calculations; bonds (chemical); graphene; nanoribbons; stress-strain relations ; ATK; Application
    Area: graphene
    BibTeX:
    @article{Liao2012,
      author = {Liao, Wenhu and Zhao, Heping and Ouyang, Gang and Chen, Ke-Qiu and Zhou, Guanghui},
      title = {Symmetry of atomistic structure for armchair-edge graphene nanoribbons under uniaxial strain},
      journal = {Applied Physics Letters},
      publisher = {AIP},
      year = {2012},
      volume = {100},
      number = {15},
      pages = {153112},
      doi = {http://dx.doi.org/10.1063/1.3702842}
    }
    
    Y. Min, J.H. Fang, C.G. Zhong & K.L. Yao Rectification effect about vacuum separating carbon nanotube bundle predicted by first-principles study 2012 Physics Letters A
    Vol. 376(23), 1845-1848 
    DOI URL 
    Abstract: For the molecular spintronics transport systems, we propose that the spin current rectifier can be constructed using the nonmagnetic lead. The proposal is confirmed according to the first-principles study of the transport characteristics of a vacuum separating (15,0) carbon nanotube bundle where only one zigzag edge is hydrogenated. The strong rectification effect for spin (charge) current is obtained in the case of the magnetic parallel (anti-parallel) configuration of two zigzag edges. Our investigations indicate that such device can be used as the spin filter and the counterpart of the p-n junction in the field of molecular electronics.
    Keywords: Non-equilibrium Green's function; Density-functional theory; Spin current; Ab initio; molecular spintronics; nanotubes; spin; MTJ; magnetoresistance; ATK; Application
    Area: nanotubes; spin; nvm
    BibTeX:
    @article{Min2012,
      author = {Min, Y. and Fang, J.H. and Zhong, C.G. and Yao, K.L.},
      title = {Rectification effect about vacuum separating carbon nanotube bundle predicted by first-principles study},
      journal = {Physics Letters A},
      year = {2012},
      volume = {376},
      number = {23},
      pages = {1845--1848},
      url = {http://www.sciencedirect.com/science/article/pii/S0375960112004756},
      doi = {http://dx.doi.org/10.1016/j.physleta.2012.04.030}
    }
    
    B. Sarikavak-Lisesivdin, S.B. Lisesivdin & E. Ozbay Ab initio study of Ru-terminated and Ru-doped armchair graphene nanoribbons 2012 Molecular Physics
    Vol. 110(18)Molecular Physics, 2295-2300 
    DOI  
    Abstract: We investigate the effects of ruthenium (Ru) termination and Ru doping on the electronic properties of armchair graphene nanoribbons (AGNRs) using first-principles methods. The electronic band structures, geometries, density of states, binding energies, band gap information, and formation energies of related structures are calculated. It is well founded that the electronic properties of the investigated AGNRs are highly influenced by Ru termination and Ru doping. With Ru termination, metallic band structures with quasi-zero-dimensional, one-dimensional and quasi-one-dimensional density of states (DOS) behavior are obtained in addition to dominant one-dimensional behavior. In contrast to Ru termination, Ru doping introduces small but measurable (12.4 to 89.6 meV) direct or indirect band gaps. These results may present an additional way to produce tunable band gaps in AGNRs.
    Keywords: ATK; Application; graphene nanoribbon; electronic-properties; edges; films
    Area: graphene
    BibTeX:
    @article{Sarikavak-Lisesivdin2012,
      author = {Sarikavak-Lisesivdin, B. and Lisesivdin, S. B. and Ozbay, E.},
      title = {Ab initio study of Ru-terminated and Ru-doped armchair graphene nanoribbons},
      booktitle = {Molecular Physics},
      journal = {Molecular Physics},
      publisher = {Taylor & Francis},
      year = {2012},
      volume = {110},
      number = {18},
      pages = {2295-2300},
      doi = {http://dx.doi.org/10.1080/00268976.2012.678905}
    }
    
    Anurag Srivastava & Neha Tyagi High pressure behavior of AlAs nanocrystals: the first-principle study 2011 High Pressure Research
    Vol. 32(1)High Pressure Research, 43-47 
    DOI  
    Abstract: In this study, the first-principle density functional approach has been used to analyze the pressure-induced structural stability and phase transformation in AlAs nanocrystals. This study includes the stability analysis of AlAs nanocrystals in their B4-, B3-, B1- and B2-type phases, and we observed that the B3-type phase is the most stable. We also observed the structural transformations in AlAs nanocrystals from B3-B1 at around 8.9 GPa, B3-B2 at 7.12 GPa and B3-B4 at 3.88 GPa. The stability of the materials has been analyzed using local density approximation with the Perdew-Zunger parameterization and also with the Perdew-Burke-Ernzerhof (PBE) and revised PBE parameterizations of the generalized gradient approximation potential.
    Keywords: ATK; Application; first principle; AlAs; phase transition; nanocrystal; generalized gradient approximation; semiconductor nanocrystals; phase-transition; GaAs
    Area: semi
    BibTeX:
    @article{Srivastava2011b,
      author = {Srivastava, Anurag and Tyagi, Neha},
      title = {High pressure behavior of AlAs nanocrystals: the first-principle study},
      booktitle = {High Pressure Research},
      journal = {High Pressure Research},
      publisher = {Taylor & Francis},
      year = {2011},
      volume = {32},
      number = {1},
      pages = {43--47},
      doi = {http://dx.doi.org/10.1080/08957959.2011.643791}
    }
    
    Xiaojin Tan, Huijin Liu, Yanwei Wen, Hongyan Lv, Lu Pan, Jing Shi & Xinfeng Tang Optimizing the thermoelectric performance of zigzag and chiral carbon nanotubes 2012 Nanoscale Research Letters
    Vol. 7(1), 116 
    DOI URL 
    Abstract: Using nonequilibrium molecular dynamics simulations and nonequilibrium Green's function method, we investigate the thermoelectric properties of a series of zigzag and chiral carbon nanotubes which exhibit interesting diameter and chirality dependence. Our calculated results indicate that these carbon nanotubes could have higher ZT values at appropriate carrier concentration and operating temperature. Moreover, their thermoelectric performance can be significantly enhanced via isotope substitution, isoelectronic impurities, and hydrogen adsorption. It is thus reasonable to expect that carbon nanotubes may be promising candidates for high-performance thermoelectric materials.
    Keywords: ATK; Application; carbon nanotube; thermoelectric properties; ZT
    Area: nanotubes; thermo
    BibTeX:
    @article{Tan2012,
      author = {Tan, Xiaojin and Liu, Huijin and Wen, Yanwei and Lv, Hongyan and Pan, Lu and Shi, Jing and Tang, Xinfeng},
      title = {Optimizing the thermoelectric performance of zigzag and chiral carbon nanotubes},
      journal = {Nanoscale Research Letters},
      year = {2012},
      volume = {7},
      number = {1},
      pages = {116},
      url = {http://www.nanoscalereslett.com/content/7/1/116},
      doi = {http://dx.doi.org/10.1186/1556-276X-7-116}
    }
    
    Haiqing Wan, Ying Xu & Guanghui Zhou Dual conductance, negative differential resistance, and rectifying behavior in a molecular device modulated by side groups 2012 J. Chem. Phys.
    Vol. 136(18), 184704-6 
    DOI  
    Abstract: We investigate the electronic transport properties for a molecular device model constructed by a phenylene ethynylene oligomer molecular with different side groups embedding in a carbon chain between two graphene electrodes. Using the first-principles method, the unusual dual conductance, negative differential resistance (NDR) behavior with large peak to valley ratio, and obvious rectifying performance are numerically observed in such proposed molecular device. The analysis of the molecular projected self-consistent Hamiltonian and the evolution of the frontier molecular orbitals (MOs) as well as transmission coefficients under various external voltage biases gives an inside view of the observed results, which suggests that the dual conductance behavior and rectifying performance are due to the asymmetry distribution of the frontier MOs as well as the corresponding coupling between the molecule and electrodes. But the NDR behavior comes from the conduction orbital being suppressed at certain bias. Interestingly, the conduction properties can be tuned by introducing side groups to the molecule and the rectification as well as the NDR behavior (peak to valley ratio) can be improved by adding different side groups in the device model.
    Keywords: molecular electronics; graphene; transport-properties; electron-transport; room-temperature; carbon; rectifiers; nanowires; negative differential resistance; NDR; rectification; ATK; Application;
    Area: molecular electronics; graphene
    BibTeX:
    @article{Wan2012,
      author = {Wan, Haiqing and Xu, Ying and Zhou, Guanghui},
      title = {Dual conductance, negative differential resistance, and rectifying behavior in a molecular device modulated by side groups},
      journal = {J. Chem. Phys.},
      publisher = {AIP},
      year = {2012},
      volume = {136},
      number = {18},
      pages = {184704--6},
      doi = {http://dx.doi.org/10.1063/1.4712615}
    }
    
    Bin Bin Wang, Feng Chao Wang & Ya Pu Zhao Understanding formation mechanism of ZnO diatomic chain and multi-shell structure using physical mechanics: Molecular dynamics and first-principle simulations 2012 Science China - Physics, Mechanics & Astronomy
    Vol. 55(6), 1138-1146 
    DOI  
    Abstract: In this paper, the possibility of the monatomic chain (MC) formation for ZnO material was studied by molecular dynamics (MD) simulation. The process of MC formation and the effects of temperature, strain rate and size were studied extensively. The tensile process can be divided to be five stages and the ZnO diatomic chain (DC) can be found. The MD results show that most atoms in MC came from the original surface of ZnO nanowires (NWs). Temperature and strain rate are two important factors affecting the process, and both high temperature and low strain rate in a certain range would be beneficial to the formation of DC. Moreover, the effects of strain rate and temperature could attribute to the Arrhenius model and the energy release mechanism. Furthermore, multi-shell structure was found for the samples under tensile strain and the layer-layer distance was about 3 Å. Our studies based on density functional theory showed that the most stable structure of ZnO DC was confirmed to be linear, and the I-V curve was also got using ATK.
    Keywords: nanowire; diatomic chain; multi-shell structure; ZnO; size effect; temperature and strain rate effects; ATK; Application
    Area: nanowires
    BibTeX:
    @article{Wang2012a,
      author = {Wang, Bin Bin and Wang, Feng Chao and Zhao, Ya Pu},
      title = {Understanding formation mechanism of ZnO diatomic chain and multi-shell structure using physical mechanics: Molecular dynamics and first-principle simulations},
      journal = {Science China - Physics, Mechanics & Astronomy},
      year = {2012},
      volume = {55},
      number = {6},
      pages = {1138-1146},
      doi = {http://dx.doi.org/10.1007/s11433-012-4760-3}
    }
    
    Chengyong Xu, Guangfu Luo, Qihang Liu, Jiaxin Zheng, Zhimeng Zhang, Shigeru Nagase, Zhengxiang Gao & Jing Lu Giant magnetoresistance in silicene nanoribbons 2012 Nanoscale
    Vol. 4(10), 3111-3117 
    DOI  
    Abstract: By performing first-principle quantum transport calculations, we predict a giant magnetoresistance in zigzag silicene nanoribbons (ZSiNRs) connecting two semi-infinite silicene electrodes through switch of the edge spin direction of ZSiNRs. Spin-filter efficiency of both the antiferromagnetic and ferromagnetic ZSiNRs is sign-changeable with the bias voltage. Therefore, potential application of silicene in spintronics devices is suggested.
    Keywords: ATK; Application; silicene nanoribbon; spin; magnetoresistance;
    Area: hexflats; spin
    BibTeX:
    @article{Xu2012a,
      author = {Xu, Chengyong and Luo, Guangfu and Liu, Qihang and Zheng, Jiaxin and Zhang, Zhimeng and Nagase, Shigeru and Gao, Zhengxiang and Lu, Jing},
      title = {Giant magnetoresistance in silicene nanoribbons},
      journal = {Nanoscale},
      publisher = {The Royal Society of Chemistry},
      year = {2012},
      volume = {4},
      number = {10},
      pages = {3111--3117},
      doi = {http://dx.doi.org/10.1039/C2NR00037G}
    }
    
    Ke Xu, Jing Huang, Zhaoyong Guan, Qunxiang Li & Jinlong Yang Transport spin polarization of magnetic C28 molecular junctions 2012 Chemical Physics Letters
    Vol. 535(0), 111-115 
    DOI URL 
    Abstract: We present a theoretical study of spin transport through a magnetic C28 molecule sandwiched between two Au (111) electrodes. The ab initio modeling is performed by spin density functional theory and nonequilibrium Green's function technique. The results clearly show that the spin-resolved transmission spectra of C28 molecular junctions exhibit robust transport spin polarization (TSP) characteristics, which depends on the contact configuration. At the small bias voltage, the conductance of C28 is mainly determined by the spin-down electrons. The TSP behavior can be effectively tuned by the gate. Our results indicate that C28 molecule holds promise in future molecular spintronics applications.
    Keywords: ATK; Application; fullerene; molecular electronics; spin transport; electron-transport; small fullerenes; spintronics; derivatives; stability; clusters; c28
    Area: fullerenes; spin
    BibTeX:
    @article{Xu2012b,
      author = {Xu, Ke and Huang, Jing and Guan, Zhaoyong and Li, Qunxiang and Yang, Jinlong},
      title = {Transport spin polarization of magnetic C28 molecular junctions},
      journal = {Chemical Physics Letters},
      year = {2012},
      volume = {535},
      number = {0},
      pages = {111--115},
      url = {http://www.sciencedirect.com/science/article/pii/S0009261412003922},
      doi = {http://dx.doi.org/10.1016/j.cplett.2012.03.066}
    }
    
    C.X. Zhang, Chaoyu He, Zhizhou Yu, L. Xue, K.W. Zhang, L.Z. Sun & Jianxin Zhong Effects of oxygen-containing defect complex on the electronic structures and transport properties of single-walled carbon nanotubes 2012 Physics Letters A
    Vol. 376(20), 1686-1691 
    DOI URL 
    Abstract: The electronic structures and transport properties of (10,0) single-walled carbon nanotube ((10,0) (SWNT)) with oxygen-containing defect complex are investigated using density functional theory in combination with nonequilibrium Green's function method. The complex delocalizes the local states of (10,0) SWNT induced by mono- and di-vacancy but strengthens the localization of the states induced by the Stone-Wales defect. As a result, the complex partially restores the transport properties of ( 10 , 0 ) SWNT with vacancies, but reduces the transmission of ( 10 , 0 ) SWNT with Stone-Wales defect. However, the oxygen-containing defect complex only slightly influences the transmission gap and threshold voltage of the system.
    Keywords: single-walled carbon nanotube; oxygen-containing defect complex; electronic structure; transport property; vacancies; field-effect transistors; augmented-wave method; adsorption; conductance; states; ATK; Application
    Area: nanotubes
    BibTeX:
    @article{Zhang2012,
      author = {Zhang, C.X. and He, Chaoyu and Yu, Zhizhou and Xue, L. and Zhang, K.W. and Sun, L.Z. and Zhong, Jianxin},
      title = {Effects of oxygen-containing defect complex on the electronic structures and transport properties of single-walled carbon nanotubes},
      journal = {Physics Letters A},
      year = {2012},
      volume = {376},
      number = {20},
      pages = {1686--1691},
      url = {http://www.sciencedirect.com/science/article/pii/S0375960112003842},
      doi = {http://dx.doi.org/10.1016/j.physleta.2012.03.052}
    }
    
    Genghong Zhang, Xin Luo, Yue Zheng & Biao Wang Giant piezoelectric resistance effect of nanoscale zinc oxide tunnel junctions: first principles simulations 2012 Phys. Chem. Chem. Phys.
    Vol. 14(19), 7051-7058 
    DOI  
    Abstract: Based on first principles simulations and quantum transport calculations, we have investigated in the present work the effect of the mechanical load on transport characteristics and the relative physical properties of nanoscale zinc oxide (ZnO) tunnel junctions, and verified an intrinsic giant piezoelectric resistance (GPR) effect. Our results show that the transport-relevant properties, e.g., the piezoelectric potential (piezopotential), built-in electric field, conduction band offset and electron transmission probability of the junction etc., can obviously be tuned by the applied strain. Accordingly, it is inspiring to find that the current-voltage characteristics and tunneling electro-resistance of the ZnO tunnel junction can significantly be adjusted with the strain. When the applied strain switches from -5% to 5%, an increase of more than 14 times in the tunneling current at a bias voltage of 1.1 V can be obtained. Meanwhile, an increase of up to 2000% of the electro-resistance ratio with respect to the zero strain state can be reached at the same bias voltage and with a 5% compression. According to our investigations, the giant piezoelectric resistance effect of nanoscale ZnO tunnel junctions exhibits great potential in exploiting tunable electronic devices. Furthermore, the methodology of strain engineering revealed in this work may shed light on the mechanical manipulations of electronic devices.
    Keywords: total-energy calculations; field-effect transistor; augmented-wave method; molecular-dynamics; nanowire; nanopiezotronics; piezotronics; interfaces; metals; piezoelectric resistance; tunnel junction; zno; strain effect; ATK; Application
    Area: interfaces; semi
    BibTeX:
    @article{Zhang2012a,
      author = {Zhang, Genghong and Luo, Xin and Zheng, Yue and Wang, Biao},
      title = {Giant piezoelectric resistance effect of nanoscale zinc oxide tunnel junctions: first principles simulations},
      journal = {Phys. Chem. Chem. Phys.},
      publisher = {The Royal Society of Chemistry},
      year = {2012},
      volume = {14},
      number = {19},
      pages = {7051--7058},
      doi = {http://dx.doi.org/10.1039/C2CP23652D}
    }
    
    P. Zhao, D.S. Liu, Y. Zhang, Y. Su, H.Y. Liu, S.J. Li & G. Chen Large Low Bias Negative Differential Resistance in an Endohedral Li@C60 Dimer Junction 2012 J. Phys. Chem. C
    Vol. 116(14)The Journal of Physical Chemistry C, 7968-7974 
    DOI  
    Abstract: By applying the nonequilibrium Green function formalism combined with density functional theory, we have investigated the electronic transport properties of the C60 dimer and its endohedral complex Li@C60 dimer. Our results show that the doping of Li atoms significantly changes the transport properties of the C60 dimer. Negative differential resistance is found in such systems. Especially, the doping of Li atoms can lead to a much larger negative differential resistance at much lower bias, and it is quite evident from the plot of differential conductance versus bias. The negative differential resistance behavior is understood in terms of the evolution of the transmission spectrum and projected density of states spectrum with applied bias combined with molecular projected self-consistent Hamiltonian states analyses.
    Keywords: ATK; Application; fullerene; transport-properties; molecular junction; carbon nanotube; atoms; temperature; c60; conductance; cluster; device; c-120
    Area: fullerenes
    BibTeX:
    @article{Zhao2012b,
      author = {Zhao, P. and Liu, D. S. and Zhang, Y. and Su, Y. and Liu, H. Y. and Li, S. J. and Chen, G.},
      title = {Large Low Bias Negative Differential Resistance in an Endohedral Li@C60 Dimer Junction},
      booktitle = {The Journal of Physical Chemistry C},
      journal = {J. Phys. Chem. C},
      publisher = {American Chemical Society},
      year = {2012},
      volume = {116},
      number = {14},
      pages = {7968--7974},
      doi = {http://dx.doi.org/10.1021/jp210880j}
    }
    
    P. Zhao & D.S. Liu First-principle study of the electronic transport properties of a new dumbbell-like carbon nanocomposite 2012 Physica B: Condensed Matter
    Vol. 407(12), 2105-2108 
    DOI URL 
    Abstract: Using a first-principle density functional theory and non-equilibrium Green's function formalism for quantum transport calculation, we have investigated the electronic transport properties of a new dumbbell-like carbon nanocomposite, in which one carbon nanotube segment is capped with two C60 fullerenes. Our results show that the current-voltage curve reveals a highly nonlinear feature. A negative differential resistance (NDR) behavior is obtained at a very low bias, which is expected to be helpful for the development of low bias NDR-based molecular devices. Moreover, the carbon nanotube length and fullerene type can affect the NDR behavior strongly. The electronic transport is analyzed from the transmission spectra and the molecular projected self-consistent Hamiltonian states under different applied biases.
    Keywords: fullerenes; non-equilibrium Green's function; Electronic transport; negative differential resistance; NDR; ATK; Application
    Area: fullerenes
    BibTeX:
    @article{Zhao2012c,
      author = {Zhao, P. and Liu, D.S.},
      title = {First-principle study of the electronic transport properties of a new dumbbell-like carbon nanocomposite},
      journal = {Physica B: Condensed Matter},
      year = {2012},
      volume = {407},
      number = {12},
      pages = {2105--2108},
      url = {http://www.sciencedirect.com/science/article/pii/S0921452612001913},
      doi = {http://dx.doi.org/10.1016/j.physb.2012.02.015}
    }
    
    P. Zhao, D.S. Liu, Y. Zhang, Y. Su, H.Y. Liu, S.J. Li & G. Chen Electronic transport properties of zigzag carbon- and boron-nitride-nanotube heterostructures 2012 Solid State Communications
    Vol. 152(12), 1061-1066 
    DOI URL 
    Abstract: Using first-principles density functional theory and non-equilibrium Green's function formalism for quantum transport calculation, we have investigated the electronic transport properties of heteronanotubes by joining a zigzag (6,0) carbon nanotube and a zigzag (6,0) boron nitride nanotube with different atomic compositions and joint configurations. Our results show that the atomic composition and joint configuration affect strongly the electronic transport properties. Obvious negative differential resistance behavior and large rectifying behavior are obtained in the heterostructure with certain composition and joint configuration. Moreover, tube length and tube radius can affect strongly the observed NDR and rectifying behaviors. The observed negative differential resistance and rectifying behaviors are explained in terms of the evolution of the transmission spectrum with applied bias combined with molecular projected self-consistent Hamiltonian states analysis.
    Keywords: carbon nanotube; boron nitride nanotube; negative differential resistance; rectifying; ATK; Application
    Area: nanotubes
    BibTeX:
    @article{Zhao2012d,
      author = {Zhao, P. and Liu, D.S. and Zhang, Y. and Su, Y. and Liu, H.Y. and Li, S.J. and Chen, G.},
      title = {Electronic transport properties of zigzag carbon- and boron-nitride-nanotube heterostructures},
      journal = {Solid State Communications},
      year = {2012},
      volume = {152},
      number = {12},
      pages = {1061--1066},
      url = {http://www.sciencedirect.com/science/article/pii/S0038109812001561},
      doi = {http://dx.doi.org/10.1016/j.ssc.2012.03.018}
    }
    
    Peng Zhao & De-Sheng Liu Electronic Transport Properties of an Anthraquinone-Based Molecular Switch with Carbon Nanotube Electrodes 2012 Chinese Physics Letters
    Vol. 29(4), 047302- 
    DOI  
    Abstract: Based on the nonequilibrium Green's function method and density functional theory calculations, we theoretically investigate the electronic transport properties of an anthraquinone-based molecular switch with carbon nanotube electrodes. The molecules that comprise the switch can convert between reduced hydroquinone (HQ) and oxidized anthraquinne (AQ) states via redox reactions. Our results show that the on-off ratio is increased one order of magnitude when compared to the case of gold electrodes. Moreover, an obvious negative differential resistance behavior at much low bias (0.07 V) is observed in the HQ form.
    Keywords: ATK; Application; nanotube; switch; negative differential resistance; conductance; devices; nanotube; molecular electronics
    Area: molecular electronics; nanotubes
    BibTeX:
    @article{Zhao2012e,
      author = {Peng Zhao and De-Sheng Liu},
      title = {Electronic Transport Properties of an Anthraquinone-Based Molecular Switch with Carbon Nanotube Electrodes},
      journal = {Chinese Physics Letters},
      year = {2012},
      volume = {29},
      number = {4},
      pages = {047302--},
      doi = {http://dx.doi.org/10.1088/0256-307X/29/4/047302}
    }
    
    Wen-Kai Zhao, Chuan-Lu Yang, Jing-Fen Zhao, Mei-Shan Wang & Xiao-Guang Ma Orientation effect on the electronic transport properties of C24 fullerene molecule 2012 Physica B: Condensed Matter
    Vol. 407(12), 2247-2253 
    DOI  
    Abstract: The transport properties of the cage-like molecule depend on its orientation between the electrodes, but the investigation on the mechanism has not been found. Using first-principle density-functional theory (DFT) and non-equilibrium Green's function (NEGF) formalism for quantum transport calculation, we study the electronic transport properties of C24 fullerene molecule with different orientations in Au-C24-Au two-probe system. The effects of k-point sampling on the Brillouin zone are explored. Our results show that the negative differential resistance of C24 molecule is found in such a system and can be tuned by the molecule's orientation in the two-probe system. We also proposed a mechanism for it. The I-V characteristic under bias voltage is determined. The present findings could be helpful for the application of the C24 molecule in the field of single molecular devices or nanometer electronics.
    Keywords: C24 fullerene; Electronic transport properties; Orientation; First-principle density-functional theory; Non-equilibrium Green's function; Negative differential resistance; ATK; Application
    Area: fullerenes
    BibTeX:
    @article{Zhao2012f,
      author = {Zhao, Wen-Kai and Yang, Chuan-Lu and Zhao, Jing-Fen and Wang, Mei-Shan and Ma, Xiao-Guang},
      title = {Orientation effect on the electronic transport properties of C24 fullerene molecule},
      journal = {Physica B: Condensed Matter},
      year = {2012},
      volume = {407},
      number = {12},
      pages = {2247--2253},
      doi = {http://dx.doi.org/10.1016/j.physb.2012.03.008}
    }
    
    Benhu Zhou, Benliang Zhou, Aihua Zeng & Guanghui Zhou Electronic transport for pristine and doped crossed graphene nanoribbon junctions with zigzag interfaces 2012 Physics Letters A
    Vol. 376(20), 1710-1713 
    DOI URL 
    Abstract: Using the fully self-consistent non-equilibrium Green's function (NEGF) method combined with density functional theory, we investigate numerically the electronic transport property for pristine and doped crossed graphene nanoribbon (GNR) junctions. It is demonstrated that in the case of zigzag interfaces, the I-V characteristics of the junction with or without doping always show semiconducting behavior, which is different from that in the case of armchair interfaces [Zhou, Liao, Zhou, Chen, Zhou, Eur. Phys. J. B 76 (2010) 421]. Interestingly, negative differential resistance (NDR) behavior can be clearly observed in a certain bias region for nitrogen-doped shoulder crossed junction. A mechanism for the NDR behavior is suggested.
    Keywords: electronic transport; graphene nanoribbon; NEGF; density functional theory; negative differential resistance; NDR; ATK; Application
    Area: graphene
    BibTeX:
    @article{Zhou2012,
      author = {Zhou, Benhu and Zhou, Benliang and Zeng, Aihua and Zhou, Guanghui},
      title = {Electronic transport for pristine and doped crossed graphene nanoribbon junctions with zigzag interfaces},
      journal = {Physics Letters A},
      year = {2012},
      volume = {376},
      number = {20},
      pages = {1710--1713},
      url = {http://www.sciencedirect.com/science/article/pii/S0375960112004392},
      doi = {http://dx.doi.org/10.1016/j.physleta.2012.04.012}
    }
    
    Kurt Stokbro, Mads Engelund & Anders Blom Atomic-scale model for the contact resistance of the nickel-graphene interface 2012 Physical Review B
    Vol. 85(16), 165442 
    DOI  
    Abstract: We perform first-principles calculations of electron transport across a nickel-graphene interface. Four different geometries are considered, where the contact area, graphene and nickel surface orientations, and the passivation of the terminating graphene edge are varied. We find covalent bond formation between the graphene layer and the nickel surface, in agreement with other theoretical studies. We calculate the energy-dependent electron transmission for the four systems and find that the systems have very similar edge contact resistance, independent of the contact area between nickel and graphene, and in excellent agreement with recent experimental data. A simple model where graphene is bonded with a metal surface shows that the results are generic for covalently bonded graphene, and the minimum attainable edge contact resistance is twice the ideal edge quantum contact resistance of graphene.
    Keywords: ATK; ATK-SE; Application; graphene; interface; contact resistance; NEGF;
    Area: graphene
    BibTeX:
    @article{Stokbro2012,
      author = {Stokbro, Kurt and Engelund, Mads and Blom, Anders},
      title = {Atomic-scale model for the contact resistance of the nickel-graphene interface},
      journal = {Physical Review B},
      publisher = {American Physical Society},
      year = {2012},
      volume = {85},
      number = {16},
      pages = {165442},
      doi = {http://dx.doi.org/10.1103/PhysRevB.85.165442}
    }
    
    Yi-Peng An, Wei Ji & Zhong-Qin Yang Z-like Conducting Pathways in Zigzag Graphene Nanoribbons with Edge Protrusions 2012 J. Phys. Chem. C
    Vol. 116(9)The Journal of Physical Chemistry C, 5915-5919 
    DOI  
    Abstract: Electronic transport properties of zigzag graphene nanoribbons (ZGNRs) with one or two triangle protrusions at the edges are studied by using density functional theory combined with nonequilibrium Green's function method. We find the protrusion generally breaks down the edge state along the same edge, which carries the most current in the junction. For the graphene ribbons having even number of zigzag chains, however, the protrusions can increase or decrease significantly the conductance with different relative position of the two protrusions, accompanied by negative differential resistance characteristics. The abnormal increase of the conductance is ascribed to the forming of a new Z-like conducting pathway as well as the ruining of the mirror symmetry of the ribbons. In terms of odd ZGNRs, the introduction of edge protrusions only suppresses current flow and linear I-V curves are achieved. These edge-modified ways make the graphene-based nanomaterials present more abundant electronic transport phenomena and can be useful for the design of future nanoelectronic devices.
    Keywords: graphene; ATK; Application: negative differential resistance; NDR
    Area: graphene
    BibTeX:
    @article{An2012,
      author = {An, Yi-Peng and Ji, Wei and Yang, Zhong-Qin},
      title = {Z-like Conducting Pathways in Zigzag Graphene Nanoribbons with Edge Protrusions},
      booktitle = {The Journal of Physical Chemistry C},
      journal = {J. Phys. Chem. C},
      publisher = {American Chemical Society},
      year = {2012},
      volume = {116},
      number = {9},
      pages = {5915--5919},
      doi = {http://dx.doi.org/10.1021/jp3003646}
    }
    
    Yi-Peng An & Zhong-Qin Yang Spin-filtering and switching effects of a single-molecule magnet Mn(dmit)[sub 2] 2012 Journal of Applied Physics
    Vol. 111(4), 043713 
    DOI  
    Abstract: We investigated spin-dependent transport properties of a single-molecule magnet Mn(dmit)2 with a coplanar or perpendicular conformation using first-principles density functional theory combined with nonequilibrium Green's function method. It was found that the current flowing through the junction comprised of two Au leads and a Mn(dmit)2 molecule is high spin-polarized, up to a high efficiency of 82%, if the two ligands of the molecule are orientated in the same plane. The current is strongly suppressed when a ligand is rotated and perpendicular to the other. These results suggest that Mn(dmit)2 is a potential candidate for spin filters or molecular switches.
    Keywords: spin polarised transport; molecular electronics; ATK; Application; single-molecule magnet; spin filter; molecular switch
    Area: molecular electronics; spin
    BibTeX:
    @article{An2012a,
      author = {An, Yi-Peng and Yang, Zhong-Qin},
      title = {Spin-filtering and switching effects of a single-molecule magnet Mn(dmit)[sub 2]},
      journal = {Journal of Applied Physics},
      publisher = {AIP},
      year = {2012},
      volume = {111},
      number = {4},
      pages = {043713},
      doi = {http://dx.doi.org/10.1063/1.3686722}
    }
    
    Can Cao, Lingna Chen, Weirong Huang & Hui Xu Electronic Transport of Zigzag Graphene Nanoribbons with Edge Hydrogenation and Oxidation 2012 The Open Chemical Physics Journal
    Vol. 4, 1-7 
    DOI  
    Abstract: By using non-equilibrium Green's functions in combination with the density-functional theory, we study the effect of zigzag graphene nanoribbons with edge hydrogenation and oxidation on transport properties. We find that for the ferromagnetic (FM) configuration the ZGNRs with CH2-CH group exhibit spin diode effect in which only one spin can occur under positive bias while the other spin occurs under negative bias. In the antiferromagnetic (AF) state the symmetric ZGNRs with CH2-CH group show the spin filter effect within some specific energy windows. However, the asymmetric ZGNRs with CH2-CH group do not show such a spin filter effect. We also find that the symmetric and asymmetric ZGNRs with C2O-CH group in AF configurations show similar transport behaviors at the Fermi level. Such ZGNRs might be exploited in spintronic nanodevices.
    Keywords: transport properties; spin-diode effect; first-principles; spin filter; ATK; Application; graphene
    Area: graphene; spin
    BibTeX:
    @article{Cao2012a,
      author = {Can Cao and Lingna Chen and Weirong Huang and Hui Xu},
      title = {Electronic Transport of Zigzag Graphene Nanoribbons with Edge Hydrogenation and Oxidation},
      journal = {The Open Chemical Physics Journal},
      year = {2012},
      volume = {4},
      pages = {1-7},
      doi = {http://dx.doi.org/10.2174/1874412501204010001}
    }
    
    J.C. Dong, H. Li, F.W. Sun & Y.F. Li Importance of Coupling Pattern and Chemical Decoration for Graphene Nanotransistors 2012 J. Phys. Chem. C
    Vol. 116(11)The Journal of Physical Chemistry C, 6762-6769 
    DOI  
    Abstract: The effects of graphene-electrode coupling pattern and chemical decoration of graphene on the electron transport properties of nanoscale graphene field effect transistors (FETs) are systematically investigated. Different from the viewpoint that molecules with thiol ending groups usually connect to Au electrodes through thiolate-gold bonds in molecular devices, the calculated electron transport properties of nanoscale graphene FETs at thiol-gold coupling mode are observed to be well consistent with experimental results. At the thiolate-gold coupling mode nanoscale graphene FETs exhibit pronounced bipolar FET characteristics with on/off ratios up to 320 (n type) and 650 (p type), which are much higher than those of large area graphene FETs. We propose that different coupling patterns between molecules and electrodes are essential factors responsible for the discrepancy between theoretical calculations and experimental studies. Moreover, the performance of nanoscale graphene FETs is observed to be effectively modulated by chemical decoration of graphene. In particular, their on/off ratios can be significantly increased by spacing groups between ending groups and graphene cores. Side substituents of graphene can regulate the performance of these FETs according to their electron-withdrawing ability. Potential implications for the design of high-performance nanoscale graphene FETs can be obtained from these results.
    Keywords: ATK-SE; Application; chemical decoration; field effect transistor;
    Area: graphene
    BibTeX:
    @article{Dong2012,
      author = {Dong, J. C. and Li, H. and Sun, F. W. and Li, Y. F.},
      title = {Importance of Coupling Pattern and Chemical Decoration for Graphene Nanotransistors},
      booktitle = {The Journal of Physical Chemistry C},
      journal = {J. Phys. Chem. C},
      publisher = {American Chemical Society},
      year = {2012},
      volume = {116},
      number = {11},
      pages = {6762--6769},
      doi = {http://dx.doi.org/10.1021/jp3005585}
    }
    
    Mohammad Khazaei, Yunye Liang, Natarajan S. Venkataramanan & Yoshiyuki Kawazoe Polymerization of cyanoacetylene under pressure: Formation of carbon nitride polymers and bulk structures 2012 Physical Review B
    Vol. 85(5), 054101- 
    DOI  
    Abstract: High-pressure phase transitions of polar and nonpolar molecular structures of cyanoacetylene (HC3N) are studied by using first-principles simulations at constant pressure. In both polar and nonpolar crystals, at pressure similar to 20 GPa, the cyanoacetylene molecules are interconnected together and form polyacrylonitrile (PA) polymers. At pressure similar to 30 GPa, PA polymers are transformed to polymers with fused pyridine rings (FPR's). The individual geometrical structures of PA and FPR polymers obtained from polar and nonpolar molecular crystals of cyanoacetylene are identical, but their stacking is different. At pressures above 40 GPa, the FPR polymers are interconnected together and new three-dimensional (3D) carbon nitride systems are formed. At ambient pressure, the long-length PA and FPR polymers are metallic, and the created 3D structures are an insulator with energy band gaps around 2.85 eV. The electron transport characteristics of FPR polymers with different lengths are investigated at finite biases by using the nonequilibrium Green's function technique combined with density functional theory (DFT) by connecting the polymers to gold electrodes. The results show that FPR polymers have negative differential resistance behavior. Our time-dependent DFT calculations reveal that FPR polymers can absorb light in the visible region. From our results, it is expected that the FPR polymers will be a good material for optoelectronic applications.
    Keywords: ATK; Application; electronic-structures; conjugated polymer; ab-initio; polyacetylene; polyacenes; phase; crystals; spectra; devices; systems
    Area: molecular electronics
    BibTeX:
    @article{Khazaei2012,
      author = {Khazaei, Mohammad and Liang, Yunye and Venkataramanan, Natarajan S. and Kawazoe, Yoshiyuki},
      title = {Polymerization of cyanoacetylene under pressure: Formation of carbon nitride polymers and bulk structures},
      journal = {Physical Review B},
      publisher = {American Physical Society},
      year = {2012},
      volume = {85},
      number = {5},
      pages = {054101--},
      doi = {http://dx.doi.org/10.1103/PhysRevB.85.054101}
    }
    
    Manabu Kiguchi, Shigeto Nakashima, Tomofumi Tada, Satoshi Watanabe, Susumu Tsuda, Yasushi Tsuji & Jun Terao Single-Molecule Conductance of pi-Conjugated Rotaxane: New Method for Measuring Stipulated Electric Conductance of pi-Conjugated Molecular Wire Using STM Break Junction 2012 Small
    Vol. 8(5), 726-730 
    DOI  
    Abstract: An electronic conductance with small fluctuations, which is stipulated in single-molecule junctions, is necessary for the precise control of single-molecule devices. However, the suppression of conductance fluctuations in conventional molecular junctions is intrinsically difficult because the fluctuations are related to the contact fluctuations and molecular motion. In the present study involving experimental and theoretical investigations, it is found that covering a single pi-conjugated wire with an alpha-cyclodextrin molecule is a promising technique for suppressing conductance fluctuations. The conductance histogram of the covered molecular junction measured with the scanning tunneling microscope break-junction technique shows that the conductance peak for the covered junction is sharper than that of the uncovered junction. The covering technique thus has two prominent effects: the suppression of intramolecular motion, and the elimination of intermolecular interactions. Theoretical calculations of electronic conductance clearly support these experimental observations.
    Keywords: rotaxane; molecular electronics; nanogap electrodes; pi-conjugated molecules; single-molecule studies; ATK; Application
    Area: molecular electronics
    BibTeX:
    @article{Kiguchi2012,
      author = {Kiguchi, Manabu and Nakashima, Shigeto and Tada, Tomofumi and Watanabe, Satoshi and Tsuda, Susumu and Tsuji, Yasushi and Terao, Jun},
      title = {Single-Molecule Conductance of pi-Conjugated Rotaxane: New Method for Measuring Stipulated Electric Conductance of pi-Conjugated Molecular Wire Using STM Break Junction},
      journal = {Small},
      publisher = {WILEY-VCH Verlag},
      year = {2012},
      volume = {8},
      number = {5},
      pages = {726--730},
      doi = {http://dx.doi.org/10.1002/smll.201102075}
    }
    
    Kai-Tak Lam & Gengchiau Liang Graphene Nanoelectronics 2012 NanoScience and Technology, 509-527  DOI  
    Abstract: Two-dimensional monolayer graphene has the unique electrical and physical properties which can be exploited in new device structures. However, its application in field-effect device structure is limited due to its semi-metal nature. Therefore, a lot of research efforts have been focussed on introducing an energy bandgap in the electronic structure. For example, a commonly studied method involves cutting two-dimensional graphene into one-dimensional narrow ribbons (graphene nanoribbons), where the spatial quantum confinement introduced by the physical edges generates an energy bandgap that is closely related to the width and edge configurations of the ribbon. Similarly for a bilayer graphene, an energy bandgap can also be obtained like the monolayer graphene nanoribbons, and be further controlled by varying its interlayer distance. In this chapter, a review of the electronic structure of monolayer graphene nanoribbon is presented and the study on the bilayer counterpart is subsequently discussed. Furthermore, based on the electrical properties of the bilayer graphene nanoribbon, the device performance of the Schottky barrier diode is investigated. Lastly, a nanoelectromechanical (NEM) switch based on the floating gate design is presented and discussed.
    Keywords: graphene; nanomechanics; ATK; Application
    Area: graphene
    BibTeX:
    @inbook{Lam2012,
      author = {Lam, Kai-Tak and Liang, Gengchiau},
      title = {Graphene Nanoelectronics},
      booktitle = {NanoScience and Technology},
      publisher = {Springer Berlin Heidelberg},
      year = {2012},
      pages = {509--527},
      doi = {http://dx.doi.org/10.1007/978-3-642-22984-8_16}
    }
    
    Jinliang Li, Zhenzhen Zhao, Cui Yu, Hongbo Wang & Jianwei Zhao Theoretical investigation on the transportation behavior of molecular wires with redox reaction 2012 Journal of Computational Chemistry
    Vol. 33(6), 666-672 
    DOI  
    Abstract: A series of model molecules [sequential quinone (Q) or hydroquinone (HQ) rings connected by triple bonds] as molecular wires have been investigated by using density functional theory combined with nonequilibrium Green's function method. The results show that the system has two discrete conductance states: a low-conductance state with Q form, and a high-conductance state with HQ form. The systematic investigations have suggested that more Q/HQ pairs in the system may improve the on/off ratio, though long molecule reduces the conductance of the molecular junction. The switch mechanism has been explained via molecular electronic structure as well as transmission spectra.
    Keywords: molecular electronics; molecular wire; transportation; nonequilibrium Green's function; electronic structure; ATK; Application
    Area: molecular electronics
    BibTeX:
    @article{Li2012a,
      author = {Li, Jinliang and Zhao, Zhenzhen and Yu, Cui and Wang, Hongbo and Zhao, Jianwei},
      title = {Theoretical investigation on the transportation behavior of molecular wires with redox reaction},
      journal = {Journal of Computational Chemistry},
      publisher = {Wiley Subscription Services, Inc., A Wiley Company},
      year = {2012},
      volume = {33},
      number = {6},
      pages = {666--672},
      doi = {http://dx.doi.org/10.1002/jcc.22895}
    }
    
    Xiao-Fei Li, Ling-Ling Wang, Ke-Qiu Chen & Yi Luo Electronic transport through zigzag/armchair graphene nanoribbon heterojunctions 2012 Journal of Physics: Condensed Matter
    Vol. 24(9), 095801 
    DOI  
    Abstract: The electronic transport properties of a graphene nanoribbon (GNR) are known to be sensitive to its width, edges and defects. We investigate the electronic transport properties of a graphene nanoribbon heterojunction constructed by fusing a zigzag and an armchair graphene nanoribbon (zGNR/aGNR) side by side. First principles results reveal that the heterojunction can be either metallic or semiconducting, depending on the width of the nanoribbons. Intrinsic rectification behaviors have been observed, which are largely sensitive to the connection length between the zGNR and aGNR. The microscopic origins of the rectification behavior have been revealed. We find that the carrier type can alter from electrons to holes with the bias voltage changing from negative to positive; the asymmetrical transmission spectra of electrons and holes induced by the interface defects directly results in the rectification behavior. The results suggest that any methods which can enhance the asymmetry of the transmission spectra between holes and electrons could be used to improve the rectification behavior in the zGNR/aGNR heterojunction. Our findings could be useful for designing graphene based electronic devices.
    Keywords: graphene heterojunction; nanoribbon; rectification; ATK; Application
    Area: graphene
    BibTeX:
    @article{Li2012c,
      author = {Xiao-Fei Li and Ling-Ling Wang and Ke-Qiu Chen and Yi Luo},
      title = {Electronic transport through zigzag/armchair graphene nanoribbon heterojunctions},
      journal = {Journal of Physics: Condensed Matter},
      year = {2012},
      volume = {24},
      number = {9},
      pages = {095801},
      doi = {http://dx.doi.org/10.1088/0953-8984/24/9/095801}
    }
    
    Ana Martín-Lasanta, Delia Miguel, Trinidad García, Juan A. López-Villanueva, Salvador Rodríguez-Bolívar, Francisco M. Gómez-Campos, Elena Buñuel, Diego J. Cárdenas, Luis Álvarez de Cienfuegos & Juan M. Cuerva Influence of the Number of Anchoring Groups on the Electronic and Mechanical Properties of Benzene-, Anthracene- and Pentacene-Based Molecular Devices 2012 ChemPhysChem
    Vol. 13(3), 860-868 
    DOI  
    Abstract: One of the central issues of molecular electronics (ME) is the study of the molecule-metal electrode contacts, and their implications for the conductivity, charge-transport mechanism, and mechanical stability. In fact, stochastic on/off switching (blinking) reported in STM experiments is a major problem of single-molecule devices, and challenges the stability and reliability of these systems. Surprisingly, the ambiguous STM results all originate from devices that bind to the metallic electrode through a one-atom connection. In the present work, DFT is employed to study and compare the properties of a set of simple acenes that bind to metallic electrodes with an increasing number of connections, in order to determine whether the increasing numbers of anchoring groups have a direct repercussion on the stability of these systems. The conductivities of the three polycyclic aromatic hydrocarbons are calculated, as well as their transmission spectra and current profiles. The thermal and mechanical stability of these systems is studied by pulling and pushing the metal-molecule connection. The results show that molecules with more than one connection per electrode exhibit greater electrical efficiency and current stability.
    Keywords: density-functional theory; au(111) surface; orbital views; conductance; junctions; gold; transport; stability; fabrication; geometry; acenes; density functional calculations; electron transport; molecular dynamics; nanotechnology; ATK; Application
    Area: molecular electronics
    BibTeX:
    @article{Martin-Lasanta2012,
      author = {Ana Martín-Lasanta and Delia Miguel and Trinidad García and Juan A. López-Villanueva and Salvador Rodríguez-Bolívar and Francisco M. Gómez-Campos and Elena Buñuel and Diego J. Cárdenas and Luis Álvarez de Cienfuegos and Juan M. Cuerva},
      title = {Influence of the Number of Anchoring Groups on the Electronic and Mechanical Properties of Benzene-, Anthracene- and Pentacene-Based Molecular Devices},
      journal = {ChemPhysChem},
      publisher = {WILEY-VCH Verlag},
      year = {2012},
      volume = {13},
      number = {3},
      pages = {860--868},
      doi = {http://dx.doi.org/10.1002/cphc.201100582}
    }
    
    Vitesh Mistry, Vihar P. Georgiev & John E. McGrady Electron transport through molecular wires based on a face-shared bioctahedral motif 2012 Comptes Rendus Chimie
    Vol. 15(2-3)Polyoxometalates, metal wires and other polymetallic complexes: structure, properties, theoretical modelling. A tribute to Marie-Madeleine Rohmer, 176-183 
    DOI URL 
    Abstract: Density functional theory in conjunction with non-equilibrium Green's functions is used to explore the electron transport properties of a series of molecules based on the face-shared bioctahedral (M2Cl9) motif. The metal-metal bond orders in the chosen molecules, [Rh2Cl9]3-, [Ru2Cl9]3- and [Mo2Cl9]3- vary from 0 (Rh) to 1 (Ru) and 3 (Mo), and the calculations indicate that there is a direct correlation between conductance and bond order. The [Mo2Cl9]3- case is particularly interesting as it is well known from crystallographic studies to be very flexible, the Mo-Mo bond length varying over a range of ~0.35 Å depending on cation. The upper limit of this range marks the point where homolytic cleavage of the sigma-pi components of the triple bond is complete, and this has a marked impact on electron transport. The localization of the metal-based orbitals means that those on the left (source) and right (drain) sides respond very differently to applied bias, giving rise to resonance effects at particular bias voltages, and hence to negative differential resistance effects.
    Keywords: density functional theory; electron transport; metal-metal bonds; ATK; Application; molecular magnet; negative differential resistance; metal-atom chains; ab-initio; carbon nanotubes; spin transport; cyclopentadienyl; conductance; benzene; complexes; junctions
    Area: molecular electronics; spin
    BibTeX:
    @article{Mistry2012,
      author = {Mistry, Vitesh and Georgiev, Vihar P. and McGrady, John E.},
      title = {Electron transport through molecular wires based on a face-shared bioctahedral motif},
      booktitle = {Polyoxometalates, metal wires and other polymetallic complexes: structure, properties, theoretical modelling. A tribute to Marie-Madeleine Rohmer},
      journal = {Comptes Rendus Chimie},
      year = {2012},
      volume = {15},
      number = {2-3},
      pages = {176--183},
      url = {http://www.sciencedirect.com/science/article/pii/S1631074811002232},
      doi = {http://dx.doi.org/10.1016/j.crci.2011.11.001}
    }
    
    Ruge Quhe, Jiaxin Zheng, Guangfu Luo, Qihang Liu, Rui Qin, Jing Zhou, Dapeng Yu, Shigeru Nagase, Wai-Ning Mei, Zhengxiang Gao & Jing Lu Tunable and sizable band gap of single-layer graphene sandwiched between hexagonal boron nitride 2012 NPG Asia Materials
    Vol. 4, e6 
    DOI  
    Abstract: Opening a tunable and sizable band gap in single-layer graphene (SLG) without degrading its structural integrity and carrier mobility is a significant challenge. Using density functional theory calculations, we show that the band gap of SLG can be opened to 0.16 eV (without an electric field) and 0.34 eV (with a strong electric field) when properly sandwiched between two hexagonal boron nitride single layers. The zero-field band gaps are increased by more than 50% when the many-body effects are included. The ab initio quantum transport simulation of a dual-gated field effect transistor (FET) made of such a sandwich structure reveals an electric-field-enhanced transport gap, and the on/off current ratio is increased by a factor of 8.0 compared with that of a pure SLG FET. The tunable and sizeable band gap and structural integrity render this sandwich structure a promising candidate for high-performance SLG FETs.
    Keywords: ATK; Application; density functional theory; electric field; graphene; h-BN sheet; quasiparticle correction; transport properties; field-effect transistor
    Area: graphene
    BibTeX:
    @article{Quhe2012,
      author = {Quhe, Ruge and Zheng, Jiaxin and Luo, Guangfu and Liu, Qihang and Qin, Rui and Zhou, Jing and Yu, Dapeng and Nagase, Shigeru and Mei, Wai-Ning and Gao, Zhengxiang and Lu, Jing},
      title = {Tunable and sizable band gap of single-layer graphene sandwiched between hexagonal boron nitride},
      journal = {NPG Asia Materials},
      publisher = {Nature Japan KK},
      year = {2012},
      volume = {4},
      pages = {e6},
      doi = {http://dx.doi.org/10.1038/am.2012.10}
    }
    
    Cai-Juan Xia, De-Sheng Liu, Han-Chen Liu & Ying-Tang Zhang Effect of Chemical Modifications on the Electronic Transport Properties of the Optical Molecular Switch 2012 Japanese Journal of Applied Physics
    Vol. 51(1), 011601 
    DOI  
    Abstract: Using first-principles density functional theory and nonequilibrium Green's function formalism, we investigate the effect of chemical modifications on the electronic transport properties of the dihydroazulene optical molecular switch. The molecule that comprises the switch can convert between the closed and the open forms upon photoexcitation. Theoretical results show that the chemical modifications play an important role in determining the switching behavior of such molecular device. This result reflects that the current ratio can be manipulated with the careful selection of the substituents and can provide fundamental guidelines for the design of functional molecular devices.
    Keywords: optical molecular switch; conductance; resistance; surface; ATK; Application
    Area: molecular electronics
    BibTeX:
    @article{Xia2012,
      author = {Cai-Juan Xia and De-Sheng Liu and Han-Chen Liu and Ying-Tang Zhang},
      title = {Effect of Chemical Modifications on the Electronic Transport Properties of the Optical Molecular Switch},
      journal = {Japanese Journal of Applied Physics},
      year = {2012},
      volume = {51},
      number = {1},
      pages = {011601},
      doi = {http://dx.doi.org/10.1143/JJAP.51.011601}
    }
    
    Peng Zhao, DeSheng Liu & Wei Liang Effects of tip separation and orientation on negative differential resistance in boron-doped carbon-nanotube-based molecular junctions 2012 Chinese Science Bulletin
    Vol. 57(9), 966-969 
    DOI  
    Abstract: We investigate using the Landauer formalism, which combines both the non-equilibrium Green's function and density functional theory, the effects of separation and orientation between two electrodes of boron-doped capped-carbon-nanotube-based molecular junctions on negative differential resistance. The results show that this negative differential resistance behavior is strongly dependent on the separation and orientation between the two electrodes. A gap width of 0.35 nm and maximal symmetry achieves the best negative differential resistance behavior.
    Keywords: ATK; Application; doping; negative differential resistance; molecular junction; carbon nanotube; non-equilibrium Green's function; density functional theory
    Area: nanotubes
    BibTeX:
    @article{Zhao2012a,
      author = {Zhao, Peng and Liu, DeSheng and Liang, Wei},
      title = {Effects of tip separation and orientation on negative differential resistance in boron-doped carbon-nanotube-based molecular junctions},
      journal = {Chinese Science Bulletin},
      year = {2012},
      volume = {57},
      number = {9},
      pages = {966-969},
      doi = {http://dx.doi.org/10.1007/s11434-012-4972-y}
    }
    
    H. Zheng, H.J. Liu, X.J. Tan, H.Y. Lv, L. Pan, J. Shi & X.F. Tang Enhanced thermoelectric performance of graphene nanoribbons 2012 Applied Physics Letters
    Vol. 100(9), 093104 
    DOI  
    Abstract: The thermoelectric properties of a series of armchair and zigzag graphene nanoribbons with narrow width are examined using nonequilibrium Green function method and molecular dynamics simulations. It is found that these nanoribbons are rather stable when the edge atoms are passivated by hydrogen and those with armchair edges exhibit much better thermoelectric performance than their zigzag counterparts. Moreover, the corresponding ZT value increases with decreasing ribbon width. By optimizing the doping level, a room temperature ZT of 6.0 can be achieved for the narrowest armchair nanoribbon. The significantly enhanced ZT value makes armchair graphene nanoribbon a promising candidate for thermoelectric applications.
    Keywords: thermoelectricity; graphene; ATK; Application
    Area: graphene; thermo
    BibTeX:
    @article{Zheng2012,
      author = {Zheng, H. and Liu, H. J. and Tan, X. J. and Lv, H. Y. and Pan, L. and Shi, J. and Tang, X. F.},
      title = {Enhanced thermoelectric performance of graphene nanoribbons},
      journal = {Applied Physics Letters},
      publisher = {AIP},
      year = {2012},
      volume = {100},
      number = {9},
      pages = {093104},
      doi = {http://dx.doi.org/10.1063/1.3689780}
    }
    
    L. Zhu, K.L. Yao & Z.L. Liu Biradical and triradical organic magnetic molecules as spin filters and rectifiers 2012 Chemical Physics
    Vol. 397(0), 1 - 8 
    DOI  
    Abstract: We have theoretically investigated the spin-polarized transport properties of molecular junctions consisting of biradical and triradical organic magnetic molecules sandwiched between two symmetric gold electrodes, respectively. It shows that these junctions function as a spin rectifier or a combination of spin and charge rectifiers with high spin rectification ratios exceeding 100, wherein the spin diode/rectification effect stems from the conjugated length and asymmetry of the molecular framework, which is the pre-requisite for electronic asymmetry of the adsorbed species. The negative differential resistance, spin-filtering and switching properties are also unveiled. In particular, it is revealed that the strong couplings between the electrodes and molecules are responsible for the negative differential resistance.
    Keywords: spin transport; organic spin rectifier; negative differential resistance; spin filtering; molecular electronics; hexadecylquinolinium tricyanoquinodimethanide; electrical rectification; transport-properties; conductance; nitroxide; monolayer; exchange; junction; ATK; Application
    Area: molecular electronics; spin
    BibTeX:
    @article{Zhu2012,
      author = {L. Zhu and K.L. Yao and Z.L. Liu},
      title = {Biradical and triradical organic magnetic molecules as spin filters and rectifiers},
      journal = {Chemical Physics},
      year = {2012},
      volume = {397},
      number = {0},
      pages = {1 - 8},
      doi = {http://dx.doi.org/10.1016/j.chemphys.2011.09.009}
    }
    
    Wei Zou, Zhizhou Yu, C.X. Zhang, J.X. Zhong & L.Z. Sun Transport properties of hybrid graphene/graphane nanoribbons 2012 Applied Physics Letters
    Vol. 100(10), 103109 
    DOI  
    Abstract: The transport properties of hybrid nanoribbons constructed by substituting zigzag graphane nanoribbons into zigzag graphene nanoribbons are investigated using the first-principles calculations and non-equilibrium Green's function. The transport properties of the hybrid systems are improved due to the appearance of transport platform with nontrivial conductance around the Fermi level. This enhancement attributes to the extra bands induced by the substituted graphane nanoribbons. Moreover, this enhancement is sensitive to the position and concentration of the substituted graphane nanoribbons in the system. Our results indicate that such hybrid system is an effective approach to modulate the transport properties of zigzag graphene nanoribbons.
    Keywords: wide band gap semiconductors; graphene; graphane; nanoribbons; ATK; Application
    Area: graphene
    BibTeX:
    @article{Zou2012,
      author = {Zou, Wei and Yu, Zhizhou and Zhang, C. X. and Zhong, J. X. and Sun, L. Z.},
      title = {Transport properties of hybrid graphene/graphane nanoribbons},
      journal = {Applied Physics Letters},
      publisher = {AIP},
      year = {2012},
      volume = {100},
      number = {10},
      pages = {103109},
      doi = {http://dx.doi.org/10.1063/1.3692725}
    }
    
    Jing Huang, Ke Xu, Shulai Lei, Haibin Su, Shangfeng Yang, Qunxiang Li & Jinlong Yang Iron-phthalocyanine molecular junction with high spin filter efficiency and negative differential resistance 2012 The Journal of Chemical Physics
    Vol. 136(6), 064707 
    DOI  
    Abstract: We investigate the spin transport properties of iron-phthalocyanine (FePc) molecule sandwiched between two N-doped graphene nanoribbons (GNRs) based on the density functional theory and nonequilibrium Green's function methods. Our calculated results clearly reveal that the FePc molecular junction has high spin-filter efficiency as well as negative differential resistance (NDR). The zero-bias conductance through FePc molecule is dominated by the spin-down electrons, and the observed NDR originates from the bias-dependent effective coupling between the FePc molecular orbitals and the narrow density of states of electrodes. The remarkable high spin-filter efficiency and NDR are robust regardless of the edge shape and the width of GNRs, and the N-doping site in GNRs. These predictions indicate that FePc junction holds great promise in molecular electronics and spintronics applications.
    Keywords: density functional theory; electrodes; electronic density of states; graphene; Green's function methods; iron compounds; nanoribbons; negative resistance; nitrogen; orbital calculations; organic compounds; spin polarised transport; graphene; molecular electronics; ATK; Application
    Area: graphene; spin
    BibTeX:
    @article{Huang2012,
      author = {Huang, Jing and Xu, Ke and Lei, Shulai and Su, Haibin and Yang, Shangfeng and Li, Qunxiang and Yang, Jinlong},
      title = {Iron-phthalocyanine molecular junction with high spin filter efficiency and negative differential resistance},
      journal = {The Journal of Chemical Physics},
      publisher = {AIP},
      year = {2012},
      volume = {136},
      number = {6},
      pages = {064707},
      doi = {http://dx.doi.org/10.1063/1.3684551}
    }
    
    X.Q. Deng, Z.H. Zhang, G.P. Tang, Z.Q. Fan, M. Qiu & C. Guo Rectifying behaviors induced by BN-doping in trigonal graphene with zigzag edges 2012 Applied Physics Letters
    Vol. 100(6), 063107 
    DOI  
    Abstract: Based on nonequilibrium Green's functions in combination with density-function theory, the transport properties of trigonal graphenes, with the vertex carbon atom substituted by one phosphorus or boron atom and bounded through a B-N pair, coupled to gold electrodes are investigated. The rectification behavior can be observed because a potential barrier similar to the p-n junction is formed in the B-N region of central molecule. When the size of a central molecule is enlarged, rectification ratio is improved greatly since the barrier height in it is enhanced as well.
    Keywords: rectification; density functional theory; doping; graphene; Green's function methods; ATK; Application
    Area: graphene
    BibTeX:
    @article{Deng2012,
      author = {Deng, X. Q. and Zhang, Z. H. and Tang, G. P. and Fan, Z. Q. and Qiu, M. and Guo, C.},
      title = {Rectifying behaviors induced by BN-doping in trigonal graphene with zigzag edges},
      journal = {Applied Physics Letters},
      publisher = {AIP},
      year = {2012},
      volume = {100},
      number = {6},
      pages = {063107},
      doi = {http://dx.doi.org/10.1063/1.3681779}
    }
    
    Hua Hao, XiaoHong Zheng, RuiNing Wang, Zhi Zeng & H.Q. Lin Spin-flip effect on transport properties of a Mn[sub 3] molecule 2012 Journal of Applied Physics
    Vol. 111(7), 07B303 
    DOI  
    Abstract: Electron transport through a single-molecule magnet [NEt4](3)[Mn3Zn2(salox)(3)O(N-3)(6)Cl-2] is investigated by spin-polarized density functional theory combined with the Keldysh nonequilibrium Green's function technique. Our study demonstrates that spin-filtering effect and negative differential resistance exist in the ground state of this molecule. When the magnetic state of the molecule is changed from its ground state to the spin-flip state, substantial changes are induced not only in energy levels of the molecule, but also in the coupling of molecular states with eigenstates of Ag(100) nano-electrodes, which lead to the disappearance of spin-filtering effect and negative differential resistance.
    Keywords: density functional theory; eigenvalues and eigenfunctions; electrodes; Green's function methods; ground states; manganese; molecular electronic states; spin polarised transport; ATK; Application; magnets
    Area: molecular electronics; spin
    BibTeX:
    @article{Hao2012a,
      author = {Hao, Hua and Zheng, XiaoHong and Wang, RuiNing and Zeng, Zhi and Lin, H. Q.},
      title = {Spin-flip effect on transport properties of a Mn[sub 3] molecule},
      journal = {Journal of Applied Physics},
      publisher = {AIP},
      year = {2012},
      volume = {111},
      number = {7},
      pages = {07B303},
      doi = {http://dx.doi.org/10.1063/1.3670984}
    }
    
    En Ling Li, Peng Fei Zhu, Tao Zhao, De Ming Ma & Xue Wen Wang Study of Electronic Structures and Transport Properties on Saturated GaN Nanowires 2012 Advanced Materials Research
    Vol. 465, 118-124 
    DOI  
    Abstract: Geometry structure, electronic structure and electronic transport properties of saturated hexagonal single crystalline GaN nanowires in the [001] growth direction have been investigated based on generalized gradient approximation (GGA) of density functional theory (DFT) and non-equilibrium Green's function (NEGF) method. The results show, there is a contraction of the bond lengths of the saturated GaN nanowires after optimization; the nanowires have direct band gap, and band gap decreases with the increase of the cross section of nanowires; the electronic density of state and electronic transmission spectra of two-probe system have their own pulse-type sharp peaks with almost the same location of electron energy; the curves of I-V characteristics of the three saturated GaN nanowires are symmetric over the entire bias-voltage range, and they are semiconducting.
    Keywords: ATK; Application; density functional theory (DFT); electronic transport; GaN nanowires
    Area: nanowires
    BibTeX:
    @article{Li2012b,
      author = {En Ling Li and Peng Fei Zhu and Tao Zhao and De Ming Ma and Xue Wen Wang},
      title = {Study of Electronic Structures and Transport Properties on Saturated GaN Nanowires},
      journal = {Advanced Materials Research},
      year = {2012},
      volume = {465},
      pages = {118-124},
      doi = {http://dx.doi.org/10.4028/www.scientific.net/AMR.465.118}
    }
    
    Chen Ming, Zheng-Zhe Lin, Jun Zhuang & Xi-Jing Ning Electronic rectification devices from carbon nanocones 2012 Applied Physics Letters
    Vol. 100(6), 063119 
    DOI  
    Abstract: The electronic rectification effects of single wall carbon nanocones (SWCNCs) with cone angles 113°, 60°, and 39° are shown by density functional theory calculation and non-equilibrium Green's functional method, and the 113° cone owns the best rectification. Based on this result, the experiment on the rectification effects of cone-like structures is explained. To realize the rectification device, a scheme for fabricating single wall carbon nanocones standing on substrates with the controlled cone shapes is suggested and was verified via molecular dynamics simulations.
    Keywords: carbon; density functional theory; Green's function methods; molecular dynamics method; molecular electronics; nanoelectronics; nanofabrication; nanostructured materials; rectification; rectifiers; ATK; Application
    Area: nanotubes; graphene
    BibTeX:
    @article{Ming2012,
      author = {Ming, Chen and Lin, Zheng-Zhe and Zhuang, Jun and Ning, Xi-Jing},
      title = {Electronic rectification devices from carbon nanocones},
      journal = {Applied Physics Letters},
      publisher = {AIP},
      year = {2012},
      volume = {100},
      number = {6},
      pages = {063119},
      doi = {http://dx.doi.org/10.1063/1.3684276}
    }
    
    Lei Shen, Tiejun Zhou, Zhaoqiang Bai, Minggang Zeng, Jing Qiang Goh, Zhi-Min Yuan, Guchang Han, Bo Liu & Yuan Ping Feng Systematic study of ferroelectric, interfacial, oxidative, and doping effects on conductance of Pt/BaTiO_3/Pt ferroelectic tunnel junctions 2012 Physical Review B
    Vol. 85(6), 064105 
    DOI  
    Abstract: Using the nonequilibrium Green's function method combined with density functional theory, we systematically study the ferroelectric, interfacial, oxidative, and doping effects on electron transport of BaTiO3-based ferroelectric tunnel junctions (Pt/BaTiO3/Pt). The ferroelectric effect reduces the tunneling conductance compared to nonferroelectric BaTiO3 due to the large decay rate of the Delta5 (py and dyz) band. The TiO2-terminated interface shows a better tunneling conductance than the BaO-terminated interface since electrons mainly transport through the Ti3d-Op bonding state. Interfacial oxidation strongly reduces the conductance due to trapping of electrons and interfacial charge localization by additional O ions, while Nb doping enhances the conductance due to the delocalized distribution of charges on orbitals of the transport channel. Our studies provide a useful guide to practical applications of tunnel junctions with ferroelectric barriers.
    Keywords: ATK; Application; interfaces; spin; ferroelectricity; MTJ;
    Area: interfaces; spin; semi; nvm
    BibTeX:
    @article{Shen2012,
      author = {Shen, Lei and Zhou, Tiejun and Bai, Zhaoqiang and Zeng, Minggang and Goh, Jing Qiang and Yuan, Zhi-Min and Han, Guchang and Liu, Bo and Feng, Yuan Ping},
      title = {Systematic study of ferroelectric, interfacial, oxidative, and doping effects on conductance of Pt/BaTiO_3/Pt ferroelectic tunnel junctions},
      journal = {Physical Review B},
      publisher = {American Physical Society},
      year = {2012},
      volume = {85},
      number = {6},
      pages = {064105},
      doi = {http://dx.doi.org/10.1103/PhysRevB.85.064105}
    }
    
    Ting-Ting Wu, Xue-Feng Wang, Ming-Xing Zhai, Hua Liu, Liping Zhou & Yong-Jin Jiang Negative differential spin conductance in doped zigzag graphene nanoribbons 2012 Applied Physics Letters
    Vol. 100(5), 052112 
    DOI  
    Abstract: The spin dependent charge transport in zigzag graphene nanoribbons (ZGNRs) has been investigated by the nonequilibrium Green's function method combined with the density functional theory at the local spin density approximation. The current versus voltage curve shows distinguished behaviors for symmetric and asymmetric ZGNRs, and the doping on the ZGNR edges can manipulate the spin transport. In special cases that a Be atom is substitutionally doped on one edge of the symmetric ZGNRs, one spin current shows negative differential resistance, whereas the other increases monotonically with the bias. This property might be used to design spin oscillators or other devices for spintronics.
    Keywords: beryllium; density functional theory; graphene; Green's function methods; nanoribbons; negative resistance; spin polarised transport; ATK; Application
    Area: graphene; spin
    BibTeX:
    @article{Wu2012a,
      author = {Ting-Ting Wu and Xue-Feng Wang and Ming-Xing Zhai and Hua Liu and Liping Zhou and Yong-Jin Jiang},
      title = {Negative differential spin conductance in doped zigzag graphene nanoribbons},
      journal = {Applied Physics Letters},
      publisher = {AIP},
      year = {2012},
      volume = {100},
      number = {5},
      pages = {052112},
      doi = {http://dx.doi.org/10.1063/1.3681775}
    }
    
    R. Chowdhury, S. Adhikari & P. Rees Graphene based single molecule nanojunction 2012 Physica B: Condensed Matter
    Vol. 407(5), 855-858 
    DOI  
    Abstract: We introduce the ab-initio framework for zigzag-edged graphene fragment based single-electron transistor (SET) operating in the Coulomb blockade regime. Graphene is modeled using the density-functional theory and the environment is described by a continuum model. The interaction between graphene and the SET environment is treated self-consistently through the Poisson equation. We calculate the charging energy as a function of an external gate potential, and from this we obtain the charge stability diagram. Specifically, the importance of including re-normalization of the charge states due to the polarization of the environment has been demonstrated.
    Keywords: Graphene fragment; Ab-initio; Single-electron transistor; Coulomb blockade; ATK; Application
    Area: graphene
    BibTeX:
    @article{Chowdhury2012,
      author = {Chowdhury, R. and Adhikari, S. and Rees, P.},
      title = {Graphene based single molecule nanojunction},
      journal = {Physica B: Condensed Matter},
      year = {2012},
      volume = {407},
      number = {5},
      pages = {855--858},
      doi = {http://dx.doi.org/10.1016/j.physb.2011.12.101}
    }
    
    Hua Hao, XiaoHong Zheng, LingLing Song, RuiNing Wang & Zhi Zeng Electrostatic Spin Crossover in a Molecular Junction of a Single-Molecule Magnet Fe_2 2012 Physical Review Letters
    Vol. 108(1), 017202- 
    DOI  
    Abstract: Spin crossover by means of an electric bias is investigated by spin-polarized density-functional theory calculations combined with the Keldysh nonequilibrium Green's technique in a molecular junction, where an individual single-molecule magnet Fe2(acpybutO)(O2CMe)(NCS)2 is sandwiched between two infinite Au(100) nanoelectrodes. Our study demonstrates that the spin crossover, based on the Stark effect, is achieved in this molecular junction under an electric bias but not in the isolated molecule under external electric fields. The main reason is that the polarizability of the molecular junction has an opposite sign to that of the isolated molecule, and thus from the Stark effect the condition for the spin crossover in the molecular junction is contrary to that in the isolated molecule.
    Keywords: ATK; Application; spin; molecular magnet; molecular junction; Stark effect;
    Area: molecular electronics; spin
    BibTeX:
    @article{Hao2012,
      author = {Hao, Hua and Zheng, XiaoHong and Song, LingLing and Wang, RuiNing and Zeng, Zhi},
      title = {Electrostatic Spin Crossover in a Molecular Junction of a Single-Molecule Magnet Fe_2},
      journal = {Physical Review Letters},
      publisher = {American Physical Society},
      year = {2012},
      volume = {108},
      number = {1},
      pages = {017202--},
      doi = {http://dx.doi.org/10.1103/PhysRevLett.108.017202}
    }
    
    Jun He & Ke-Qiu Chen Humidity effects on the electronic transport properties in carbon based nanoscale device 2012 Physics Letters A
    Vol. 376(6-7), 869-874 
    DOI  
    Abstract: By applying nonequilibrium Green's functions in combination with the density functional theory, we investigate the effect of humidity on the electronic transport properties in carbon based nanoscale device. The results show that different humidity may form varied localized potential barrier, which is a very important factor to affect the stability of electronic transport in the nanoscale system. A mechanism for the humidity effect is suggested.
    Keywords: humidity effect; fullerenes and related materials; electronic transport; first-principles; nanotube; ATK; Application
    Area: nanotubes; fullerenes
    BibTeX:
    @article{He2012,
      author = {He, Jun and Chen, Ke-Qiu},
      title = {Humidity effects on the electronic transport properties in carbon based nanoscale device},
      journal = {Physics Letters A},
      year = {2012},
      volume = {376},
      number = {6-7},
      pages = {869--874},
      doi = {http://dx.doi.org/10.1016/j.physleta.2012.01.026}
    }
    
    Guomin Ji, Dongmei Li, Changfeng Fang, Yuqing Xu, Yaxin Zhai, Bin Cui & Desheng Liu Effect of contact interface configuration on electronic transport in (C20)2-based molecular junctions 2012 Physics Letters A
    Vol. 376(5), 773-778 
    DOI  
    Abstract: Using first-principles calculations, we study the electronic transport properties in Au(C20)2Au molecular junctions with different contact interface configurations: point contact and bond contact. We observe that the transmission through the bond contact is considerably higher than that of point contact. Furthermore, the I-V characteristics are rather different. For the bond contact, we get a metallic behavior followed by a varistor-type behavior. While as for the point contact, the current increases very slowly in a nonlinear way and is one order of magnitude smaller than that of bond contact. We attribute these obvious differences to the distinct contact configurations.
    Keywords: Molecular electronics; First-principles; Electron transport; C20; fullerene; ATK; Application
    Area: fullerenes; molecular electronics
    BibTeX:
    @article{Ji2012,
      author = {Ji, Guomin and Li, Dongmei and Fang, Changfeng and Xu, Yuqing and Zhai, Yaxin and Cui, Bin and Liu, Desheng},
      title = {Effect of contact interface configuration on electronic transport in (C20)2-based molecular junctions},
      journal = {Physics Letters A},
      year = {2012},
      volume = {376},
      number = {5},
      pages = {773--778},
      doi = {http://dx.doi.org/10.1016/j.physleta.2011.12.025}
    }
    
    Jianming Jia, Shin-Pon Ju, Daning Shi & Kuan-Fu Lin Electrical transport through heterojunctions of single-walled carbon/silicon carbide/carbon nanotubes 2012 Journal of Applied Physics
    Vol. 111(1), 013704 
    DOI  
    Abstract: The transport properties of heterojunctions composed of SiC nanotubes (SiCNTs) with different length coupled between metallic carbon nanotubes (CNTs) have been investigated using a combined density-functional theory and nonequilibrium Green's function formalism. It is shown that the conductance of heterojunction decreases exponentially with the increasing length of SiCNT. The current-voltage curve of the system is linear for short SiCNT, but becomes gradually nonlinear for longer SiCNT, indicating a transition from metallic characteristics to semiconductor-like behavior. The observed trends can be understood by the electron tunneling between metallic CNTs. The present results provide insights into the physical mechanism of heterojunctions and are useful for their applications in electronic devices.
    Keywords: carbon nanotubes; density functional theory; Green's function methods; semiconductor heterojunctions; silicon compounds; tunnelling; wide band gap semiconductors; ATK; Application
    Area: nanotubes
    BibTeX:
    @article{Jia2012,
      author = {Jianming Jia and Shin-Pon Ju and Daning Shi and Kuan-Fu Lin},
      title = {Electrical transport through heterojunctions of single-walled carbon/silicon carbide/carbon nanotubes},
      journal = {Journal of Applied Physics},
      publisher = {AIP},
      year = {2012},
      volume = {111},
      number = {1},
      pages = {013704},
      doi = {http://dx.doi.org/10.1063/1.3673793}
    }
    
    Yong-Jun Li, Ming-Da Li, Jian-Shuang Liu, Qing-Qing Sun, Peng Zhou, Peng-Fei Wang, Shi-Jin Ding & David Wei Zhang Atomic scale investigation of the abnormal transport properties in bilayer graphene nanoribbon 2012 Applied Physics Letters
    Vol. 100(1), 013110-3 
    DOI  
    Abstract: We investigate the transport properties of bilayer AA-stacking zigzag graphene nanoribbons (bi-zGNRs) and observe abnormal I-V characteristics which are sensitive to the number of carbon chains across the ribbons. Combining the chirality selective rule of Dirac electrons in graphene and the symmetry of eigenstates, we attribute the abnormal current behavior to the chirality mismatch of energy states. The mismatch causes the suppression of transmission pathways between two electrodes which lead to saturated current with increasing bias for certain ribbons.
    Keywords: carrier mobility; chirality; eigenvalues and eigenfunctions; energy states; bilayer graphene nanoribbon; nanostructured materials; ATK; Application
    Area: graphene
    BibTeX:
    @article{Li2012,
      author = {Li, Yong-Jun and Li, Ming-Da and Liu, Jian-Shuang and Sun, Qing-Qing and Zhou, Peng and Wang, Peng-Fei and Ding, Shi-Jin and Zhang, David Wei},
      title = {Atomic scale investigation of the abnormal transport properties in bilayer graphene nanoribbon},
      journal = {Applied Physics Letters},
      publisher = {AIP},
      year = {2012},
      volume = {100},
      number = {1},
      pages = {013110--3},
      doi = {http://dx.doi.org/10.1063/1.3673324}
    }
    
    Z.Z. Lin, J. Zhuang & X.J. Ning High-efficient tunable infrared laser from monatomic carbon chains 2012 EPL (Europhysics Letters)
    Vol. 97(2), 27006 
    DOI  
    Abstract: Based on ab initio calculations, short B-doped monatomic carbon chains (MCCs) are suggested to serve as working medium for tunable infrared lasers. The MCCs derived from single-layer graphene in vacuum are proved to be very stable at room temperature, and their band gap is quite stretching-controllable with corresponding laser wavelength varying in the range 870-4590 nm, which is not easy to be implemented via previous techniques. High electro-optical conversion efficiency can be achieved by simply applying electric voltage on the chain ends and the MCC lasers are naturally polarized.
    Keywords: electro-optical; ATK; Application; carbon chain;
    Area: nanowires
    BibTeX:
    @article{Lin2012,
      author = {Z. Z. Lin and J. Zhuang and X. J. Ning},
      title = {High-efficient tunable infrared laser from monatomic carbon chains},
      journal = {EPL (Europhysics Letters)},
      year = {2012},
      volume = {97},
      number = {2},
      pages = {27006},
      doi = {http://dx.doi.org/10.1209/0295-5075/97/27006}
    }
    
    H.Y. Lv, H.J. Liu, X.J. Tan, L. Pan, Y.W. Wen, J. Shi & X.F. Tang The properties of BiSb nanoribbons from first-principles calculations 2012 Nanoscale
    Vol. 4(2), - 
    DOI  
    Abstract: The structural, electronic and magnetic properties of BiSb nanoribbons (BSNRs) with different widths and edge configurations are investigated via the first-principles pseudopotential method. It is found that the pristine BSNRs with armchair edges (ABSNRs) are semiconductors and the band gaps exhibit a width dependent odd-even oscillation. In contrast, the pristine BSNRs with zigzag edges (ZBSNRs) are found to be metallic. When all the edge atoms are passivated by hydrogen, both the ABSNRs and ZBSNRs become semiconducting and the corresponding band gaps decrease monotonically with the increasing width. If, however, the edge atoms are partially passivated, the ABSNRs can be either semiconducting or metallic. Moreover, local magnetism appears when all the edge Sb atoms are passivated and there are one or more unsaturated Bi atoms. Using the nonequilibrium Green's function (NEGF) approach, we find that all the investigated odd-numbered ABSNRs have almost the same peak value of the power factor around the Fermi level. This is not the case for the even-numbered ABSNRs, where the peaks are twice that of when they are n-type doped. Our calculations indicate that BSNRs can have a very high room temperature figure of merit (ZT value), which makes them very promising candidates for thermoelectric applications.
    Keywords: BiSb nanoribbons; spin; figure of merit; ZT; ab initio molecular-dynamics; nanowires; transport-properties; graphene nanoribbons; semiconductor transition; thermoelectric materials; electronic-structure; thin-films; exfoliation; devices; ATK; Application
    Area: graphene; spin; thermo
    BibTeX:
    @article{Lv2012,
      author = {Lv, H. Y. and Liu, H. J. and Tan, X. J. and Pan, L. and Wen, Y. W. and Shi, J. and Tang, X. F.},
      title = {The properties of BiSb nanoribbons from first-principles calculations},
      journal = {Nanoscale},
      publisher = {The Royal Society of Chemistry},
      year = {2012},
      volume = {4},
      number = {2},
      pages = {--},
      doi = {http://dx.doi.org/10.1039/C1NR11585E}
    }
    
    Yukihito Matsuura Spin transport in poly(metalarenylsilane) 2012 Applied Physics Letters
    Vol. 100(5), 053303 
    DOI  
    Abstract: We focused on the spin transport properties of polymers containing ferrocene and the related transition-metal-benzene sandwich compound (metal=Cr and V) with a silicon bridge such as poly(ferrocenylsilane) and poly(metalarenylsilane). As a model system, a sulfur-substituted oligomer was put on gold electrodes via the sulfur-gold interaction. Spin transport between the two gold electrodes was calculated using a non-equilibrium Green's function formalism and density functional theory. We have found that the oligomer containing Cr or V atoms exhibited an almost perfect spin filter behavior in which all the 3dz2 orbitals contributed to the electron transport.
    Keywords: band structure; density functional theory; Green's function methods; polymers; spin polarised transport; ATK; Application
    Area: molecular electronics; spin
    BibTeX:
    @article{Matsuura2012,
      author = {Matsuura, Yukihito},
      title = {Spin transport in poly(metalarenylsilane)},
      journal = {Applied Physics Letters},
      publisher = {AIP},
      year = {2012},
      volume = {100},
      number = {5},
      pages = {053303},
      doi = {http://dx.doi.org/10.1063/1.3680590}
    }
    
    Zeyuan Ni, Qihang Liu, Kechao Tang, Jiaxin Zheng, Jing Zhou, Rui Qin, Zhengxiang Gao, Dapeng Yu & Jing Lu Tunable Bandgap in Silicene and Germanene 2011 Nano Letters
    Vol. 12(1)Nano Letters, 113-118 
    DOI  
    Abstract: By using ab initio calculations, we predict that a vertical electric field is able to open a band gap in semimetallic single-layer buckled silicene and germanene. The sizes of the band gap in both silicene and germanene increase linearly with the electric field strength. Ab initio quantum transport simulation of a dual-gated silicene field effect transistor confirms that the vertical electric field opens a transport gap, and a significant switching effect by an applied gate voltage is also observed. Therefore, biased single-layer silicene and germanene can work effectively at room temperature as field effect transistors.
    By using ab initio calculations, we predict that a vertical electric field is able to open a band gap in semimetallic single-layer buckled silicene and germanene. The sizes of the band gap in both silicene and germanene increase linearly with the electric field strength. Ab initio quantum transport simulation of a dual-gated silicene field effect transistor confirms that the vertical electric field opens a transport gap, and a significant switching effect by an applied gate voltage is also observed. Therefore, biased single-layer silicene and germanene can work effectively at room temperature as field effect transistors.
    Keywords: ATK; Application; silicene; germanene; band gap; quantum transport; electric field; first-principles calculation
    Area: hexflats
    BibTeX:
    @article{Ni2011,
      author = {Ni, Zeyuan and Liu, Qihang and Tang, Kechao and Zheng, Jiaxin and Zhou, Jing and Qin, Rui and Gao, Zhengxiang and Yu, Dapeng and Lu, Jing},
      title = {Tunable Bandgap in Silicene and Germanene},
      booktitle = {Nano Letters},
      journal = {Nano Letters},
      publisher = {American Chemical Society},
      year = {2011},
      volume = {12},
      number = {1},
      pages = {113--118},
      doi = {http://dx.doi.org/10.1021/nl203065e}
    }
    
    Dan Erik Petersen, Hans Henrik B. Sørensen, Per Christian Hansen, Stig Skelboe & Kurt Stokbro Block tridiagonal matrix inversion and fast transmission calculations 2008 Journal of Computational Physics
    Vol. 227(6), 3174-3190 
    DOI  
    Abstract: A method for the inversion of block tridiagonal matrices encountered in electronic structure calculations is developed, with the goal of efficiently determining the matrices involved in the Fisher-Lee relation for the calculation of electron transmission coefficients. The new method leads to faster transmission calculations compared to traditional methods, as well as freedom in choosing alternate Green's function matrix blocks for transmission calculations. The new method also lends itself to calculation of the tridiagonal part of the Green's function matrix. The effect of inaccuracies in the electrode self-energies on the transmission coefficient is analyzed and reveals that the new algorithm is potentially more stable towards such inaccuracies.
    Keywords: Matrix inversion; Electron transport; Transmission; Density functional theory; ATK; Background; Application
    Area:
    BibTeX:
    @article{Petersen2008,
      author = {Petersen, Dan Erik and Sørensen, Hans Henrik B. and Hansen, Per Christian and Skelboe, Stig and Stokbro, Kurt},
      title = {Block tridiagonal matrix inversion and fast transmission calculations},
      journal = {Journal of Computational Physics},
      year = {2008},
      volume = {227},
      number = {6},
      pages = {3174--3190},
      doi = {http://dx.doi.org/10.1016/j.jcp.2007.11.035}
    }
    
    You Qian, Kai-Tak Lam, Chengkuo Lee & Gengchiau Liang The effects of interlayer mismatch on electronic properties of bilayer armchair graphene nanoribbons 2012 Carbon
    Vol. 50(4), 1659-1666 
    DOI  
    Abstract: We investigate the impact of interlayer mismatch on the electronic properties of bilayer graphene nanoribbons (BGNRs) with armchair-edges in terms of the total energy and electronic structures by first principle calculations. Simulation results show that in-plane misalignments require little energy and a large variation in the energy bandgap (EG) can be observed. Based on the resulting atomic configurations due to the misalignments, the details of the observed relationship between bandgap and the lattice mismatch are investigated. It is observed that in general, misalignment in the transverse direction results in a decrease in the interaction between the two layers, giving rise to a larger EG. On the other hand, misalignment in the longitudinal direction, i.e. along the edges, leads to an oscillation in EG due to the periodic change of the GNR stacking order. A combination of these movements results in a complex variation of EG, which introduces great uncertainty in electronic devices. However, such a phenomenon could also be used in various kinds of nanoelectromechanical systems as it provides a large change in electronic properties with a small movement.
    Keywords: bilayer graphene nanoribbon; ATK; Application; nanoelectromechanics
    Area: graphene
    BibTeX:
    @article{Qian2012,
      author = {Qian, You and Lam, Kai-Tak and Lee, Chengkuo and Liang, Gengchiau},
      title = {The effects of interlayer mismatch on electronic properties of bilayer armchair graphene nanoribbons},
      journal = {Carbon},
      year = {2012},
      volume = {50},
      number = {4},
      pages = {1659--1666},
      doi = {http://dx.doi.org/10.1016/j.carbon.2011.12.007}
    }
    
    Yuta Tsuji, Aleksandar Staykov & Kazunari Yoshizawa Molecular Rectifier Based on pi-pi Stacked Charge Transfer Complex 2012 Journal of Physical Chemistry C
    Vol. 116(3)The Journal of Physical Chemistry C, 2575-2580 
    DOI  
    Abstract: Electron transport through pi-stacked materials has been studied theoretically and experimentally so far with versatile applications in mind. In this paper a novel pi-stacked molecular rectifier is proposed. Electron transport properties through cyclophane-type quinhydrone are investigated by using nonequilibrium Green's function method combined with density functional theory. The investigated molecule has a quinhydrone structure comprised of pi-stacked donor (hydroquinone) and acceptor (benzoquinone) pair due to the in-phase orbital interaction between the HOMO of hydroquinone and the LUMO of benzoquinone. A computed current-voltage curve shows rectifying behavior in the direction perpendicular to the ring plane. The maximum value of rectification ratio of 2.37 is obtained at 0.8 V. In this system the LUMO level plays a key role, and asymmetrical evolution of the LUMO level for positive and negative biases leads to the rectifying behavior. The present study is a basic step for further functionalization of a molecular rectifier based on transannular electron transport. The understanding of insight into the electron transport through a pi-stacked system will provide motivation for design of future molecular devices.
    Keywords: molecular electronics; ATK; Application; rectification; molecular devices
    Area: molecular electronics
    BibTeX:
    @article{Tsuji2011a,
      author = {Tsuji, Yuta and Staykov, Aleksandar and Yoshizawa, Kazunari},
      title = {Molecular Rectifier Based on pi-pi Stacked Charge Transfer Complex},
      booktitle = {The Journal of Physical Chemistry C},
      journal = {Journal of Physical Chemistry C},
      publisher = {American Chemical Society},
      year = {2012},
      volume = {116},
      number = {3},
      pages = {2575--2580},
      doi = {http://dx.doi.org/10.1021/jp209547a}
    }
    
    Haiqing Wan, Benhu Zhou, Xiongwen Chen, Chang Q. Sun & Guanghui Zhou Switching, Dual Spin-Filtering Effects, and Negative Differential Resistance in a Carbon-Based Molecular Device 2012 Journal of Physical Chemistry C
    Vol. 116(3)The Journal of Physical Chemistry C, 2570-2574 
    DOI  
    Abstract: We present ab initio calculations for spin-dependent electron transport in a molecular device constructed by two carbon chains capped with a phenyl ring, which is sandwiched between two zig-zag-edged graphene nanoribbon (ZGNR) electrodes, where the ZGNRs are modulated by external magnetic field. The coexistence of switching, dual spin-filtering effects, and negative differential resistance (NDR) in the model device is demonstrated with the theory of carbon pi-electrons. Interestingly, a two-state molecular conformational switch can be realized by changing the orientation between the planes of phenyl ring and electrodes, where the majority-spin current modulation (ON/OFF ratio) is 170-479 within the considered bias window. Moreover, the device shows perfect dual spin-filtering effect and can generate and control a full dual spin-polarized current through either the source-drain voltage or magnetic configuration of the electrodes. The selective spin current is due to a dual selection rule, the symmetry match between two ZGNR electrodes spin channel, and the carbon chain's spin selection in our system. In addition, the obvious NDR behavior has also been observed in our model.
    Keywords: ATK; Application; graphene; spin filter; negative differential resistance; NDR;
    Area: graphene; spin
    BibTeX:
    @article{Wan2011,
      author = {Wan, Haiqing and Zhou, Benhu and Chen, Xiongwen and Sun, Chang Q. and Zhou, Guanghui},
      title = {Switching, Dual Spin-Filtering Effects, and Negative Differential Resistance in a Carbon-Based Molecular Device},
      booktitle = {The Journal of Physical Chemistry C},
      journal = {Journal of Physical Chemistry C},
      publisher = {American Chemical Society},
      year = {2012},
      volume = {116},
      number = {3},
      pages = {2570--2574},
      doi = {http://dx.doi.org/10.1021/jp2092576}
    }
    
    Jinying Wang, Zhongfan Liu & Zhirong Liu First-principles study of the transport behavior of zigzag graphene nanoribbons tailored by strain 2012 AIP Advances
    Vol. 2(1), 012103 
    DOI  
    Abstract: The charge transport properties of zigzag graphene nanoribbons (ZGNRs) under uniaxial and shear strains are theoretically studied. Although all strained ZGNRs have similar metallic band structures, they show four types of transport behavior under bias voltages that depend on the type of strain and the mirror symmetry of the ZGNR. Under an applied uniaxial strain, the current of symmetric ZGNRs is consistently small, while for asymmetric ZGNRs it is large. In contrast, the current increases with increasing shear strain for symmetric ZGNRs while it decreases for asymmetric ZGNRs. The current properties merge when the shear strain exceeds a critical value, and the two systems then show similar behavior. Our results suggest that strained ZGNRs with an appropriate applied shear are ideal conducting wires.
    Keywords: ab initio calculations; band structure; graphene; strain; ATK; Application
    Area: graphene
    BibTeX:
    @article{Wang2012,
      author = {Jinying Wang and Zhongfan Liu and Zhirong Liu},
      title = {First-principles study of the transport behavior of zigzag graphene nanoribbons tailored by strain},
      journal = {AIP Advances},
      publisher = {AIP},
      year = {2012},
      volume = {2},
      number = {1},
      pages = {012103},
      doi = {http://dx.doi.org/10.1063/1.3676615}
    }
    
    Xiao-Lin Wei, Yuan-Ping Chen, Wen-Liang Liu & Jian-Xin Zhong Enhanced gas sensor based on nitrogen-vacancy graphene nanoribbons 2012 Physics Letters A
    Vol. 376(4), 559-562 
    DOI  
    Abstract: We study the electron transport of nitrogen-vacancy zigzag graphene nanoribbons (ZGNRs) absorbing gas molecules. It is found that the nitrogen-vacancy ZGNRs are more sensitive to the gas molecules than the pristine ZGNRs. The gas molecules absorbed on the three-nitrogen vacancies lead to sharp resonant peaks on conductance, while those absorbed on the four-nitrogen vacancies lead to anti-resonant dips. Each kind of gas molecule can be detected by its own unique (different energy) resonant peaks (or dips). This indicates that the nitrogen vacancy can enhance the sensitivity to gas molecules, i.e., nitrogen-vacancy ZGNRs can serve as better gas sensors.
    Keywords: Nitrogen vacancy; Graphene nanoribbons; Electron transport; Gas sensor; ATK; Application
    Area: graphene
    BibTeX:
    @article{Wei2012,
      author = {Wei, Xiao-Lin and Chen, Yuan-Ping and Liu, Wen-Liang and Zhong, Jian-Xin},
      title = {Enhanced gas sensor based on nitrogen-vacancy graphene nanoribbons},
      journal = {Physics Letters A},
      year = {2012},
      volume = {376},
      number = {4},
      pages = {559--562},
      doi = {http://dx.doi.org/10.1016/j.physleta.2011.10.055}
    }
    
    Yihong Wu, Ying Wang, Jiayi Wang, Miao Zhou, Aihua Zhang, Chun Zhang, Yanjing Yang, Younan Hua & Baoxi Xu Electrical transport across metal/two-dimensional carbon junctions: Edge versus side contacts 2012 AIP Advances
    Vol. 2(1), 012132 
    DOI  
    Abstract: Metal/two-dimensional carbon junctions are characterized by using a nanoprobe in an ultrahigh vacuum environment. Significant differences were found in bias voltage (V) dependence of differential conductance (dI/dV) between edge- and side-contact; the former exhibits a clear linear relationship (i.e., dI/dV propto V), whereas the latter is characterized by a nonlinear dependence, dI/dV propto V^(3/2). Theoretical calculations confirm the experimental results, which are due to the robust two-dimensional nature of the carbon materials under study. Our work demonstrates the importance of contact geometry in graphene-based electronic devices.
    Keywords: metal-insulator boundaries; graphene; experimental comparison; ATK; Application
    Area: graphene
    BibTeX:
    @article{Wu2012,
      author = {Wu, Yihong and Wang, Ying and Wang, Jiayi and Zhou, Miao and Zhang, Aihua and Zhang, Chun and Yang, Yanjing and Hua, Younan and Xu, Baoxi},
      title = {Electrical transport across metal/two-dimensional carbon junctions: Edge versus side contacts},
      journal = {AIP Advances},
      publisher = {AIP},
      year = {2012},
      volume = {2},
      number = {1},
      pages = {012132},
      doi = {http://dx.doi.org/10.1063/1.3684617}
    }
    
    J. Zhou, L. Wang, R. Qin, J.X. Zheng, W.N. Mei, P.A. Dowben, S. Nagase, Z.X. Gao & J. Lu Structure and Electronic and Transport Properties of Transition Metal Intercalated Graphene and Graphene-Hexagonal-Boron-Nitride Bilayer 2011 Journal of Physical Chemistry C
    Vol. 115(51), 25273-25280 
    DOI  
    Abstract: Structural, electronic, and magnetic properties of the Fe-, Co-, Ni-, and V-intercalated graphene bilayer sandwich (denoted by C(2)vertical bar M vertical bar C(2), M = Fe, Co, Ni, and V) and graphene on hexagonal boron nitride (h-BN) bilayer sandwich (denoted by C(2)vertical bar M vertical bar BN, M = Fe, Co, Ni, and V) are studied by using density functional theory method. We find that both the graphene bilayer and graphene-h-BN bilayer in all the C(2)vertical bar M vertical bar C(2) and C(2)vertical bar M vertical bar BN sandwiches favor AB stacking over AA stacking mode. The Fe, Co, and Ni atoms prefer to be located over the center of C-C bonds whereas V atoms prefer to be located above the C atoms on graphene, and they all prefer to be located above the N atoms on h-BN sheet, regardless of the stacking mode. The C(2)vertical bar Fe vertical bar C(2), C(2)vertical bar CO vertical bar C(2), C(2)vertical bar Fe vertical bar BN, and C(2)vertical bar Co vertical bar BN sandwiches of AB stacking are all ferromagnetic metals with the spin polarization of 86%, 67%, 65%, and 46% at the Fermi level, respectively. By contrast, both C(2)vertical bar Ni vertical bar C(2) and C(2)vertical bar Ni vertical bar BN sandwiches of AB stacking are nonmagnetic semiconductors with bandgaps of 0.64 and 0.23 eV, respectively, which provide a novel strategy of opening a bandgap of graphene. From the quantum transport calculation, we obtain a giant room-temperature magnetoresistance of similar to 200% in the spin valve device based on AB stacking C(2)vertical bar Fe vertical bar C(2) sandwich.
    Keywords: field-effect transistors; room-temperature; magnetoresistance; graphite; gap; graphene bilayer; boron-nitride; Application; ATK
    Area: graphene; spin
    BibTeX:
    @article{Zhou2011b,
      author = {Zhou, J. and Wang, L. and Qin, R. and Zheng, J. X. and Mei, W. N. and Dowben, P. A. and Nagase, S. and Gao, Z. X. and Lu, J.},
      title = {Structure and Electronic and Transport Properties of Transition Metal Intercalated Graphene and Graphene-Hexagonal-Boron-Nitride Bilayer},
      journal = {Journal of Physical Chemistry C},
      publisher = {Amer Chemical Soc},
      year = {2011},
      volume = {115},
      number = {51},
      pages = {25273--25280},
      doi = {http://dx.doi.org/10.1021/jp209468f}
    }
    
    Zhaoqiang Bai, Yongqing Cai, Lei Shen, Ming Yang, Viloane Ko, Guchang Han & Yuanping Feng Magnetic and transport properties of Mn[sub 3 - x]Ga/MgO/Mn[sub 3 - x]Ga magnetic tunnel junctions: A first-principles study 2012 Applied Physics Letters
    Vol. 100(2), 022408 
    DOI  
    Abstract: Magnetic and transport properties of Mn[3-x]Ga/MgO/Mn[3-x]Ga (0<=x<=1) magnetic tunnel junctions are studied using first-principles approach based on density functional theory and non-equilibrium Green's function. Perpendicular magnetization, of which the magnetic anisotropy energy reaches more than 1 meV/unit-cell, is confirmed to be energetically favoured by both Mn2Ga and Mn3Ga thin films. Furthermore, despite high spin-polarization at the Fermi energy for both these compounds as reported, our transport calculation shows considerable disparity in the transmission behaviour between Mn2Ga/MgO/Mn2Ga(001) and Mn3Ga/MgO/Mn_3Ga(001) magnetic tunnel junctions: huge optimistic tunneling magnetoresistance ratio of 103% for the former, and nevertheless, no tunneling magnetoresistance effect absolutely for the latter. This phenomenon is attributed to the symmetry selective filtering effect of the MgO spacer. On this premise, Mn[3-x]Ga compounds with low Mn concentration are predicted to be promising candidate materials to serve as the electrodes of spin-transfer torque devices in the next-generation data storage technique.
    Keywords: ab initio calculations; density functional theory; Fermi level; gallium alloys; Green's function methods; magnesium compounds; magnetic multilayers; magnetic thin films; manganese alloys; MIM structures; perpendicular magnetic anisotropy; spin polarised transport; tunnelling magnetoresistance; ATK; Application
    Area: interfaces; spin; semi; nvm
    BibTeX:
    @article{Bai2012,
      author = {Zhaoqiang Bai and Yongqing Cai and Lei Shen and Ming Yang and Viloane Ko and Guchang Han and Yuanping Feng},
      title = {Magnetic and transport properties of Mn[sub 3 - x]Ga/MgO/Mn[sub 3 - x]Ga magnetic tunnel junctions: A first-principles study},
      journal = {Applied Physics Letters},
      publisher = {AIP},
      year = {2012},
      volume = {100},
      number = {2},
      pages = {022408},
      doi = {http://dx.doi.org/10.1063/1.3676195}
    }
    
    Changfeng Fang, Dongmei Li, Bin Cui, Yuqing Xu, Guomin Ji & Desheng Liu Effect of different electrodes on Fano resonance in molecular devices 2012 Applied Physics Letters
    Vol. 100(2), 023303 
    DOI  
    Abstract: By using nonequilibrium Green's function in combination with density functional theory, we study the electronic transport properties of two typical pi-conjugated molecules (dithiol-benzene and C4S2), sandwiched between two metallic electrodes made of different metals. The presence of two different electrodes leads to Fano resonances at certain energy. As a consequence, electronic transport in future molecular electric circuits can be substantially affected when the molecular devices placed between electrodes with different chemical potentials. The Fano line shapes reveal that there is nonresonant channel when two asymmetric electrodes are employed.
    Keywords: density functional theory; electrodes; electron spin polarisation; Green's function methods; molecular electronics; photoemission; ATK; Application
    Area: molecular electronics; spin
    BibTeX:
    @article{Fang2012,
      author = {Changfeng Fang and Dongmei Li and Bin Cui and Yuqing Xu and Guomin Ji and Desheng Liu},
      title = {Effect of different electrodes on Fano resonance in molecular devices},
      journal = {Applied Physics Letters},
      publisher = {AIP},
      year = {2012},
      volume = {100},
      number = {2},
      pages = {023303},
      doi = {http://dx.doi.org/10.1063/1.3676190}
    }
    
    Yukihito Matsuura Spin transport in bimetallic pentalene complexes 2011 Solid State Communications
    Vol. 151(24), 1877 - 1880 
    DOI  
    Abstract: Spin transport in bimetallic pentalene complexes (CpM(pentalene)M'Cp;M,M'=Fe,Co,Ni) between two gold electrodes was investigated, using a Green's function formalism under density functional theory. Variation of the metal atom species in the complexes gives a considerable change in their spin properties, with hetero-bimetallic complexes containing an odd number of electrons exhibiting spin filter behaviour. In contrast, alternation in the contact condition, whether Cp-anchoring or adducting by sulphur-gold bonds, had almost no effect on spin filter behaviour, but did lead to variation in electrical conduction. We examined suitable bimetallic pentalene complexes in order to enhance their spin filter efficiency.
    Keywords: Bimetallic pentalene complex; spin transport; DFT; ATK; Application; molecular electronics
    Area: molecular electronics; spin
    BibTeX:
    @article{Matsuura2011,
      author = {Yukihito Matsuura},
      title = {Spin transport in bimetallic pentalene complexes},
      journal = {Solid State Communications},
      year = {2011},
      volume = {151},
      number = {24},
      pages = {1877 - 1880},
      doi = {http://dx.doi.org/10.1016/j.ssc.2011.10.001}
    }
    
    Yongqing Cai, Aihua Zhang, Yuan Ping Feng & Chun Zhang Switching and rectification of a single light-sensitive diarylethene molecule sandwiched between graphene nanoribbons 2011 The Journal of Chemical Physics
    Vol. 135(18), 184703 
    DOI URL 
    Abstract: The "open" and "closed" isomers of the diarylethene molecule that can be converted between each other upon photo-excitation are found to have drastically different current-voltage characteristics when sandwiched between two graphene nanoribbons (GNRs). More importantly, when one GNR is metallic and another one is semiconducting, strong rectification behavior of the "closed" diarylethene isomer with the rectification ratio >10^3 is observed. The surprisingly high rectification ratio originates from the band gap of GNR and the bias-dependent variation of the lowest unoccupied molecular orbital of the diarylethene molecule, the combination of which completely shuts off the current at positive biases. Results presented in this paper may form the basis for a new class of molecular electronic devices.
    Keywords: graphene nanoribbon; molecular electronic states; nanostructured materials; optical materials; rectification; ATK; Application
    Area: graphene
    BibTeX:
    @article{Cai2011a,
      author = {Yongqing Cai and Aihua Zhang and Yuan Ping Feng and Chun Zhang},
      title = {Switching and rectification of a single light-sensitive diarylethene molecule sandwiched between graphene nanoribbons},
      journal = {The Journal of Chemical Physics},
      publisher = {AIP},
      year = {2011},
      volume = {135},
      number = {18},
      pages = {184703},
      url = {http://arxiv.org/abs/1111.1811},
      doi = {http://dx.doi.org/10.1063/1.3657435}
    }
    
    C. Cao, L.N. Chen, D. Zhang, W.R. Huang, S.S. Ma & H. Xu Electronic properties and conductance suppression of defected and doped zigzag graphene nanoribbons 2012 Solid State Communications
    Vol. 152(1), 45 - 49 
    DOI  
    Abstract: By using the first-principles calculation based on density functional theory, we investigate the electronic structures and transport properties of the defected and doped zigzag graphene nanoribbons (ZGNRs). The effects of multivacancies defects and impurities have been considered. The results show that band structures of ZGNRs can be tuned strongly and currents drop drastically due to the defect and impurities. Moreover, the notable suppression of conductance can be found near the Fermi level, leading to the negative differential resistance (NDR) behavior under low bias. This effect presents a possibility in novel nanoelectronics devices application.
    Keywords: graphene nanoribbons; electronic structures and transport property; impurity; defect; first-principles; ATK; Application
    Area: graphene
    BibTeX:
    @article{Cao2012,
      author = {C. Cao and L.N. Chen and D. Zhang and W.R. Huang and S.S. Ma and H. Xu},
      title = {Electronic properties and conductance suppression of defected and doped zigzag graphene nanoribbons},
      journal = {Solid State Communications},
      year = {2012},
      volume = {152},
      number = {1},
      pages = {45 - 49},
      doi = {http://dx.doi.org/10.1016/j.ssc.2011.10.004}
    }
    
    Jianming Jia, Shin-Pon Ju, Daning Shi & Kuan-Fu Lin Electromechanical Response of a SiC Nanotube under Local Torsional Deformation 2011 The Journal of Physical Chemistry C
    Vol. 115(49), 24347-24352 
    DOI  
    Abstract: The electromechanical properties of a SiC nanotube under local torsional deformation have been characterized for the single-walled (7,0) zigzag model using a combined formalism of density functional theory and nonequilibrium Green's function. It is shown that, with the increase of torsion angle, the SiC nanotube undergoes, in turn, the structural evolution with the circular section retained and torsional buckling until complete failure. The local deformation has a significant effect on the transport properties of the nanotube, resulting in the torsion-dependent transport spectrum and current–voltage characteristics. The variation of the current at a given bias with the torsion angle can be attributed to the local-torsion-induced energy shift of edge states in the twisted region of the SiC nanotube.
    Keywords: ATK; Application; SiC nanotube; electromechanical properties;
    Area: nanotubes
    BibTeX:
    @article{Jia2011,
      author = {Jia, Jianming and Ju, Shin-Pon and Shi, Daning and Lin, Kuan-Fu},
      title = {Electromechanical Response of a SiC Nanotube under Local Torsional Deformation},
      journal = {The Journal of Physical Chemistry C},
      year = {2011},
      volume = {115},
      number = {49},
      pages = {24347-24352},
      doi = {http://dx.doi.org/10.1021/jp207857e}
    }
    
    Xiao-Fei Li, Ling-Ling Wang, Ke-Qiu Chen & Yi Luo Tuning the Electronic Transport Properties of Zigzag Graphene Nanoribbons via Hydrogenation Separators 2011 The Journal of Physical Chemistry C
    Vol. 115(49), 24366-24372 
    DOI  
    Abstract: Hydrogenation technique is known to be useful for opening up the band gap and controlling the electronic properties of the graphene. We have demonstrated with first principles calculations that the hydrogenation can be used to make separators to electrically separate zigzag graphene nanoribbons (zGNR) and tune their transport properties. First principles calculations reveal that each hydrogenation separator can introduce two conducting edge-like states into the subbands around the Fermi level, which can greatly enhance the conductance of the system. We find that the zGNRs with hydrogenation separators are still spin polarized; the distributions of spin densities are mainly located along the two edges of the pristine nanoribbon and the borders of the separators. The current polarization shows a nice oscillation behavior as a function of the position of the separator, which originates from the symmetry dependent transport character of the zGNRs. Moreover, we find that the hydrogenation separators can screen the impact of rough edges, which makes rough-edge zGNRs behave like smooth-edge zGNRs. Our findings could be very useful for designing electronic devices based on the hydrogenation of graphene nanoribbons.
    Keywords: ATK; Application; graphene nanoribbon; hydrogenation; spin
    Area: graphene; spin
    BibTeX:
    @article{Li2011f,
      author = {Li, Xiao-Fei and Wang, Ling-Ling and Chen, Ke-Qiu and Luo, Yi},
      title = {Tuning the Electronic Transport Properties of Zigzag Graphene Nanoribbons via Hydrogenation Separators},
      journal = {The Journal of Physical Chemistry C},
      year = {2011},
      volume = {115},
      number = {49},
      pages = {24366-24372},
      doi = {http://dx.doi.org/10.1021/jp208892h}
    }
    
    Haiying Liu, Genqin Li, Hongqi Ai, Jilai Li & Yuxiang Bu Electronic Enhancement Effect of Copper Modification of Base Pairs on the Conductivity of DNA 2011 The Journal of Physical Chemistry C
    Vol. 115(45), 22547-22556 
    DOI  
    Abstract: The effect of the new designed multicopper modification of base pairs on the conductivity of DNA was investigated by the nonequilibrium Green's function method combined with density functional theory. Electronic transport calculations revealed that the equi-number H-by-Cu replacement can significantly enhance the conductivity of DNA from two aspects: transverse base-to-base communication along the hydrogen-bond direction and longitudinal transport along the DNA duplex. Furthermore, the enhancement effect on the longitudinal direction is more notable than that on the transverse. A tunneling mechanism is suggested for the short DNA segments. The decay factor of conductance in Cu-DNA decreases by half compared with the native DNA, thus making it more promising for constructing nanowires. In addition, Cu-DNA may prefer electron migration to hole transport with the lengthening of DNA segments. This work will shed some light on the design of promising DNA-based molecular wires.
    Keywords: ATK; Application; molecular electronics; DNA base pairs;
    Area: molecular electronics
    BibTeX:
    @article{Liu2011f,
      author = {Liu, Haiying and Li, Genqin and Ai, Hongqi and Li, Jilai and Bu, Yuxiang},
      title = {Electronic Enhancement Effect of Copper Modification of Base Pairs on the Conductivity of DNA},
      journal = {The Journal of Physical Chemistry C},
      year = {2011},
      volume = {115},
      number = {45},
      pages = {22547-22556},
      doi = {http://dx.doi.org/10.1021/jp2070198}
    }
    
    E. Nadimi, P. Planitz, R. Ottking, M. Schreiber & C. Radehaus First-principles investigation of the leakage current through strained SiO2 gate dielectrics in MOSFETs 2011 Semiconductor Conference Dresden (SCD), 2011, 1-4  DOI  
    Abstract: A combination of density functional theory and non-equilibrium Green's function formalism has been applied to the atomic scale calculation of the leakage current through the strained SiO2 dielectric layer of MOSFETs. This first-principles approach accounts for intrinsic strain at the Si/SiO2 interface as well as its influence on the leakage current. Furthermore, the impact of external mechanical stress on the leakage current was investigated. It is shown that compression of atomic layers along the direction perpendicular to the interface results in a lower tunneling probability and leakage current while the tensile strain in that direction leads to higher tunneling probability and consequently higher leakage current. Based on this behavior we give an explanation for the increase of the tunneling effective mass of electrons as the thickness of the dielectric layer decreases in terms of intrinsic strain at the Si/SiO2 interface.
    Keywords: MOSFET; Si-SiO2; atomic layers; density functional theory; dielectric layer; external mechanical stress; first-principles investigation; intrinsic strain; leakage current; nonequilibrium Green function formalism; strained gate dielectrics; tensile strain; tunneling effective mass; tunneling probability; Green's function methods; MOSFET; leakage currents; silicon compounds; tunnelling; ATK; Application; interface
    Area: interfaces; semi
    BibTeX:
    @inproceedings{Nadimi2011,
      author = {Nadimi, E. and Planitz, P. and Ottking, R. and Schreiber, M. and Radehaus, C.},
      title = {First-principles investigation of the leakage current through strained SiO2 gate dielectrics in MOSFETs},
      booktitle = {Semiconductor Conference Dresden (SCD), 2011},
      year = {2011},
      pages = {1-4},
      doi = {http://dx.doi.org/10.1109/SCD.2011.6068768}
    }
    
    Y.-H. Tang, V.M.K. Bagci, Jing-Han Chen & Chao-Cheng Kaun Conductance of Stretching Oligothiophene Single-Molecule Junctions: A First-Principles Study 2011 The Journal of Physical Chemistry C
    Vol. 115(50), 25105-25108 
    DOI  
    Abstract: We analyze conductance switching properties during the stretching of Au-oligothiophene dimethylene dithiol-Au single-molecule junctions, by using first-principles calculations based on the density functional theory and the nonequilibrium Green's function approach. Our results of these sigma-pi hybrid molecular systems agree well with the experimental data and confirm that the longer molecular junction (four thiophene rings) has higher conductance than the shorter one (three thiophene rings). We attribute this behavior to their differently located molecular levels, with respect to the Fermi energy, at the point of the junction break. This breaking point, occurring at a longer stretching distance for the shorter molecule, affects the junction conductance significantly and can be determined by several characteristics of the junction.
    Keywords: ATK; Application; molecular electronics; switching;
    Area: molecular electronics
    BibTeX:
    @article{Tang2011,
      author = {Tang, Y.-H. and Bagci, V. M. K. and Chen, Jing-Han and Kaun, Chao-Cheng},
      title = {Conductance of Stretching Oligothiophene Single-Molecule Junctions: A First-Principles Study},
      journal = {The Journal of Physical Chemistry C},
      year = {2011},
      volume = {115},
      number = {50},
      pages = {25105-25108},
      doi = {http://dx.doi.org/10.1021/jp209671v}
    }
    
    Zhongchang Wang, Mitsuhiro Saito, Susumu Tsukimoto & Yuichi Ikuhara Heterointerfaces: atomic structures, electronic states, and related properties 2011 Journal of the Ceramic Society of Japan
    Vol. 119(1395), 783-793 
    DOI  
    Abstract: Recent breakthroughs in transmission electron microscopy enable a direct quantitative determination of the technologically significant heterointerfaces, yet a direct interpretation is not always possible. Here, we review the general processes to introduce the high-precision first-principles calculations into the microscopy in order to obtain an atomistic understanding of effects of buried interfaces on a wide range of properties. We demonstrate the possibility and important advance of this combined method in relating interface structures to device physics even for the complex heterointerfaces, SiC/Ti3SiC2, La[x]Sr[1-x]O/(SrTiO3)n, and Pd/ZnO presented here. We therefore believe that this approach should be widely applicable to many other interfaces and a range of materials, providing new insights into many long-standing unresolved issues regarding interfaces.
    Keywords: ATK; Application; buried interfaces; experimental comparison
    Area: interfaces; semi
    BibTeX:
    @article{Wang2011c,
      author = {Zhongchang Wang and Mitsuhiro Saito and Susumu Tsukimoto and Yuichi Ikuhara},
      title = {Heterointerfaces: atomic structures, electronic states, and related properties},
      journal = {Journal of the Ceramic Society of Japan},
      year = {2011},
      volume = {119},
      number = {1395},
      pages = {783-793},
      doi = {http://dx.doi.org/10.2109/jcersj2.119.783}
    }
    
    Lu Wang, Jiaxin Zheng, Jing Zhou, Rui Qin, Hong Li, Wai-Ning Mei, Shigeru Nagase & Jing Lu Tuning graphene nanoribbon field effect transistors via controlling doping level 2011 Theoretical Chemistry Accounts: Theory, Computation, and Modeling (Theoretica Chimica Acta)
    Vol. 130, 483-489 
    DOI  
    Abstract: By performing first-principles transport simulations, we demonstrate that n-type transfer curves can be obtained in armchair-edged graphene nanoribbon field effect transistors by the potassium atom and cobaltocene molecule doping, or substituting the carbon by nitrogen atom. The Dirac point shifts downward from 0 to -12 V when the n-type impurity concentration increases from 0 to 1.37%, while the transfer curves basically maintain symmetric feature with respect to the Dirac point. In general, the on/off current ratios are decreased and subthreshold swings are increased with the increasing doping level. Therefore, the performance of armchair-edged graphene nanoribbon field effect transistors can be controlled via tuning the impurity doping level.
    Keywords: graphene nanoribbon; field effect transistor; ab initio calculation; ATK; Application
    Area: graphene
    BibTeX:
    @article{Wang2011d,
      author = {Wang, Lu and Zheng, Jiaxin and Zhou, Jing and Qin, Rui and Li, Hong and Mei, Wai-Ning and Nagase, Shigeru and Lu, Jing},
      title = {Tuning graphene nanoribbon field effect transistors via controlling doping level},
      journal = {Theoretical Chemistry Accounts: Theory, Computation, and Modeling (Theoretica Chimica Acta)},
      publisher = {Springer Berlin / Heidelberg},
      year = {2011},
      volume = {130},
      pages = {483-489},
      doi = {http://dx.doi.org/10.1007/s00214-011-1026-5}
    }
    
    Yuqing Xu, Changfeng Fang, Guomin Ji, Wei Du, Dongmei Li & Desheng Liu Electrostatic current switching and negative differential resistance behavior in a molecular device based on carbon nanotubes 2012 Phys. Chem. Chem. Phys.
    Vol. 14(2), 668-674 
    DOI  
    Abstract: The electronic transport properties of an all-carbon mechanically controlled molecular device based on carbon nanotubes are studied using non-equilibrium Green's function in combination with density functional theory. A segment of (10,0) single-walled carbon nanutube (SWCNT) is placed concentrically outside a (5,0) SWCNT, namely, a (5,0)@(10,0) double-walled carbon nanotube (DWCNT). It is found that the position, orientation and length scaling of the (10,0) SWCNT have crucial effects on the electronic transport properties of the system. When the (10,0) SWCNT is mechanically pushed forward along the axial direction, alternation of on/off switching behavior under low bias and negative differential resistance behavior under high bias are observed. Significant changes in the electronic transport properties arise when rotating the (10,0) SWCNT around the common axis or adding carbon atom layers in the transport direction. Theoretical explanations are proposed for these phenomena.
    Keywords: ATK; Application; nanotube; mechanically controlled molecular device;
    Area: nanotubes
    BibTeX:
    @article{Xu2012,
      author = {Xu, Yuqing and Fang, Changfeng and Ji, Guomin and Du, Wei and Li, Dongmei and Liu, Desheng},
      title = {Electrostatic current switching and negative differential resistance behavior in a molecular device based on carbon nanotubes},
      journal = {Phys. Chem. Chem. Phys.},
      year = {2012},
      volume = {14},
      number = {2},
      pages = {668-674},
      doi = {http://dx.doi.org/10.1039/C1CP22882J}
    }
    
    Shan-Sheng Yu, Chun Wang, Wei-Tao Zheng & Qing Jiang Mechanical and electron-transport properties of graphene nanoribbons under tensile strain: A first-principles study 2011 physica status solidi (a)
    Vol. 208(10), 2328-2331 
    DOI  
    Abstract: We calculate the mechanical and electron-transport properties of graphene nanoribbons (GNRs) under uniaxial tensile strain with first-principles density functional theory. Our calculations reveal that armchair- and zigzag-shaped edges decrease and increase the tensile strength of GNR, respectively. The I-V curve for GNR with armchair edges changes drastically under tensile strain, while the influence of tensile strain on the electron-transport properties of GNR with zigzag edges is negligible. Our calculations propose one way to design and fabricate nanoscale mechanical sensors and devices based on GNRs.
    Keywords: ATK; Application; density functional theory; electronic structure; graphene nanoribbons; mechanical properties; molecular electronic devices; transport; magnetoresistance; nanoribbons
    Area: graphene
    BibTeX:
    @article{Yu2011d,
      author = {Yu, Shan-Sheng and Wang, Chun and Zheng, Wei-Tao and Jiang, Qing},
      title = {Mechanical and electron-transport properties of graphene nanoribbons under tensile strain: A first-principles study},
      journal = {physica status solidi (a)},
      publisher = {WILEY-VCH Verlag},
      year = {2011},
      volume = {208},
      number = {10},
      pages = {2328--2331},
      doi = {http://dx.doi.org/10.1002/pssa.201084168}
    }
    
    Lili Yu, Xin Yan, Hong Li, Rui Qin, Guangfu Luo, Chengyong Xu, Jiaxin Zheng, Qihang Liu, Jing Lu, Zhengxiang Gao & Xuefeng Wang Negative rectification and negative differential resistance in nanoscale single-walled carbon nanotube p-n junctions 2011 Theoretical Chemistry Accounts: Theory, Computation, and Modeling (Theoretica Chimica Acta)
    Vol. 130, 353-359 
    DOI  
    Abstract: We investigate the transport properties of few-nm-long single-walled carbon nanotube (SWCNT) p - n junctions for the first time by using ab initio quantum transport calculations. Unlike the previously reported few-micrometer-long SWCNT p - n junctions, which rectify positively, all the investigated ultrashort SWCNT p - n junctions show negative rectification effect, accompanied by negative differential resistance.
    Keywords: single-walled carbon nanotube; p-n junctions; rectification; negative differential resistance; NDR; ATK; Application
    Area: nanotubes
    BibTeX:
    @article{Yu2011e,
      author = {Yu, Lili and Yan, Xin and Li, Hong and Qin, Rui and Luo, Guangfu and Xu, Chengyong and Zheng, Jiaxin and Liu, Qihang and Lu, Jing and Gao, Zhengxiang and Wang, Xuefeng},
      title = {Negative rectification and negative differential resistance in nanoscale single-walled carbon nanotube p-n junctions},
      journal = {Theoretical Chemistry Accounts: Theory, Computation, and Modeling (Theoretica Chimica Acta)},
      publisher = {Springer Berlin / Heidelberg},
      year = {2011},
      volume = {130},
      pages = {353-359},
      doi = {http://dx.doi.org/10.1007/s00214-011-0990-0}
    }
    
    Jing Zeng, Ke-Qiu Chen, Jun He, Xiao-Jiao Zhang & Chang Q. Sun Edge Hydrogenation-Induced Spin-Filtering and Rectifying Behaviors in the Graphene Nanoribbon Heterojunctions 2011 The Journal of Physical Chemistry C
    Vol. 115(50), 25072-25076 
    DOI  
    Abstract: By using nonequilibrium Green's functions in combination with the density functional theory, we investigate the electronic transport properties of edge hydrogenated zigzag-edged graphene nanoribbon heterojunctions. Results show that a perfect spin-filtering effect with 100% spin polarization and a rectifying behavior with a ratio larger than 10^5 can be realized by dihydrogenation, which can also be modulated by changing the widths of the two component ribbons.
    Keywords: ATK; Application; graphene nanoribbon heterojunction; spin filter; hydrogenation; rectification
    Area: graphene; spin
    BibTeX:
    @article{Zeng2011g,
      author = {Zeng, Jing and Chen, Ke-Qiu and He, Jun and Zhang, Xiao-Jiao and Sun, Chang Q.},
      title = {Edge Hydrogenation-Induced Spin-Filtering and Rectifying Behaviors in the Graphene Nanoribbon Heterojunctions},
      journal = {The Journal of Physical Chemistry C},
      year = {2011},
      volume = {115},
      number = {50},
      pages = {25072-25076},
      doi = {http://dx.doi.org/10.1021/jp208248v}
    }
    
    P. Zhao, D.S. Liu & M. Yuan Rectifying properties of a boron/nitrogen-doped C131-based molecular junction: A first-principles study 2012 Physica B: Condensed Matter
    Vol. 407(1), 73-76 
    DOI  
    Abstract: Using first-principles density functional theory and non-equilibrium Green's function formalism for quantum transport calculation, we have investigated the electronic transport properties of the boron/nitrogen-doped C131-based molecular junction. Our results show that an obvious rectifying behavior is observed. Moreover, the rectifying performance can be tuned by adjusting the doping sites. The mechanism for the rectifying phenomenon is suggested. The present findings could be helpful for the application of the C131 molecule in the field of single molecular devices or nanometer electronics.
    Keywords: doping; fullerene; molecular electronics; rectification; ATK; Application
    Area: molecular electronics; fullerenes
    BibTeX:
    @article{Zhao2012,
      author = {P. Zhao and D. S. Liu and M. Yuan},
      title = {Rectifying properties of a boron/nitrogen-doped C131-based molecular junction: A first-principles study},
      journal = {Physica B: Condensed Matter},
      year = {2012},
      volume = {407},
      number = {1},
      pages = {73-76},
      doi = {http://dx.doi.org/10.1016/j.physb.2011.09.123}
    }
    
    Ping Bai, Kai Tak Lam, Erping Li & K.K. f. Chang A Comprehensive Atomic Study of Carbon Nanotube Schottky Diode Using First Principles Approach 2007 Electron Devices Meeting, 2007. IEDM 2007. IEEE International, 749-752  DOI  
    Abstract: In this paper, Carbon nanotube (CNT) Schottky diodes are investigated from the atomic perspective using the first principles DFT-NEGF method. Two atomic models are built based on experimental setting. The atomic behaviors of the CNT Schottky diodes are explored through density of states and charge transfer of the atomic models. The electron transport properties of the CNT diodes are analyzed through transmission function, energy gap shifting and I-V characteristics.
    Keywords: DFT-NEGF method; I-V characteristics; atomic models; carbon nanotube Schottky diode; charge transfer; comprehensive atomic study; energy gap shifting; Schottky diodes; carbon nanotubes; charge exchange; ATK; Application
    Area: nanotubes
    BibTeX:
    @inproceedings{Bai2007a,
      author = {Ping Bai and Kai Tak Lam and Erping Li and Chang, K.K.-f.},
      title = {A Comprehensive Atomic Study of Carbon Nanotube Schottky Diode Using First Principles Approach},
      booktitle = {Electron Devices Meeting, 2007. IEDM 2007. IEEE International},
      publisher = {IEEE, 345 E 47th St, New York, NY 10017 USA},
      year = {2007},
      pages = {749-752},
      doi = {http://dx.doi.org/10.1109/IEDM.2007.4419055}
    }
    
    S. Choudhary & S. Qureshi Vacancy Defect Reconstruction and its Effect on Electron Transport in Si-c Nanotubes 2011 J. Nano- Electron. Phys.
    Vol. 3(1), 1035-1040 
    URL 
    Abstract: We investigate the vacancy defect reconstruction and its effect on I-V characteristics in a (4, 0) zigzag and (5, 5) armchair silicon-carbide nanotubes (SiCNTs) by applying self consistent non-equilibrium Green's function formalism in combination with the density-functional theory to a two probe molecular junction constructed from SiCNTs. The results show that single vacancies and di-vacancies in SiCNTs have different reconstructions. A single vacancy when optimized, reconstructs into a 5-1DB configuration in both zigzag and armchair SiCNTs, and a di-vacancy reconstructs into a 5-8-5 configuration in zigzag and into a 5-2DB configuration in armchair SiCNTs. Introduction of vacancy increases the band gap of (4, 0) metallic SiCNT and decreases the bandgap of (5, 5) semiconducting SiCNT, bias voltage dependent current characteristic show reduction in overall current in metallic SiCNT and an increase in overall current in semiconducting SiCNT.
    Keywords: nanotube; sicnt; armchair-zigzag; defects; vacancy; ATK; Application
    Area: nanotubes
    BibTeX:
    @article{Choudhary2011c,
      author = {Choudhary, S. and Qureshi, S.},
      title = {Vacancy Defect Reconstruction and its Effect on Electron Transport in Si-c Nanotubes},
      journal = {J. Nano- Electron. Phys.},
      publisher = {World Scientific Publ Co Pte Ltd},
      year = {2011},
      volume = {3},
      number = {1},
      pages = {1035-1040},
      url = {http://jnep.sumdu.edu.ua/en/component/content/full_article/287}
    }
    
    Haixia Da, Yuan Ping Feng & Gengchaiu Liang Transition-Metal-Atom-Embedded Graphane and Its Spintronic Device Applications 2011 The Journal of Physical Chemistry C
    Vol. 115(46), 22701-22706 
    DOI  
    Abstract: First-principles calculations are implemented to investigate the electronic and magnetic properties of transition-metal (TM)-atom-embedded graphanes. We find that most of the configurations possess magnetic ground states that have larger magnetic moments compared to embedding TM atoms in graphenes. Furthermore, the various magnetic moments can be generated by tailoring the different dopants. We also design a heterojunction structure with nickel- and vanadium-embedded graphanes in order to manipulate the spin currents. Due to the materials' unique characteristics, the spin-down current can be totally suppressed while the spin-up current appears under a negative bias voltage, resulting in a perfect spin filter and spin current diode. Such properties imply promising potential applications in graphane-based nanodevices and spintronics.
    Keywords: ATK; Application; graphene; graphane; transition metals; magnetic moment; spin;
    Area: graphene; spin
    BibTeX:
    @article{Da2011,
      author = {Da, Haixia and Feng, Yuan Ping and Liang, Gengchaiu},
      title = {Transition-Metal-Atom-Embedded Graphane and Its Spintronic Device Applications},
      journal = {The Journal of Physical Chemistry C},
      year = {2011},
      volume = {115},
      number = {46},
      pages = {22701-22706},
      doi = {http://dx.doi.org/10.1021/jp203506z}
    }
    
    Z.Q. Fan & K.Q. Chen Theoretical Investigation of Gate Voltage Controllable Transport Properties In Single C(60) Molecular Device 2011 International Journal of Modern Physics B
    Vol. 25(29), 3871-3880 
    DOI  
    Abstract: The effect of gate voltage on electronic transport properties in single C(60) molecular device is investigated by a first-principles method based on density functional theory and nonequilibrium Green's function formalism. The calculated results show that the variation of the equilibrium conductance with gate voltage strongly corresponds with the variation of transmission eigenvalues and depends on the shift of molecular orbitals. The positive gate voltage can enhance the device's electronic transport, while negative gate voltage weaken it, which shows a gate-controlled molecular current switch. More importantly, the negative differential resistance behavior is observed and can be modulated by the gate potential. A detailed explanations for these phenomena are given.
    Keywords: field-effect transistors; negative differential-resistance; electron-transport; intermolecular interaction; carbon nanotubes; room-temperature; conductance; junctions; 1st-principles; oscillations; ATK; Application; gates; fullerene
    Area: fullerenes
    BibTeX:
    @article{Fan2011b,
      author = {Fan, Z. Q. and Chen, K. Q.},
      title = {Theoretical Investigation of Gate Voltage Controllable Transport Properties In Single C(60) Molecular Device},
      journal = {International Journal of Modern Physics B},
      publisher = {World Scientific Publ Co Pte Ltd},
      year = {2011},
      volume = {25},
      number = {29},
      pages = {3871--3880},
      doi = {http://dx.doi.org/10.1142/S0217979211102034}
    }
    
    C.X. Zhang, Chaoyu He, Zhizhou Yu, K.W. Zhang, L.Z. Sun & Jianxin Zhong Transport Properties of Zigzag Graphene Nanoribbons Decorated by Carboxyl Group Chains 2011 The Journal of Physical Chemistry C
    Vol. 115(44), 21893-21898 
    DOI URL 
    Abstract: The transport properties of zigzag graphene nanoribbons (ZGNRs) decorated by carboxyl group (OH) chains are systematically investigated using the density functional theory in combination with the nonequilibrium Green's function method. ZGNRs with nine zigzag carbon chains (9ZGNR) decorated by mOH (m is the number of oxidized carbon chains) are taken as typical systems. We find that the OH chains can effectively modulate the electronic structures and transport properties of the 9ZGNR. The systems behave as metal when m <= 4, and a transmission plateau up to 6G0 is found around the Fermi level when m = 3. However, when m > 4, the 9ZGNR-mOH systems become semiconductors. Interestingly, 9ZGNR-7OH and 9ZGNR-8OH behave as n-type semiconductors. It is found that such modulation depends on the edge states as well as the oxygen atoms at the interface. When the width of undecorated carbon regions is <3, Peierls instability induces the metal-semiconductor transition.
    Keywords: ATK; Application; graphene; total-energy calculations; augmented-wave method; graphite oxide; basis-set; phase; films; gas; Peierls instability; metal-semiconductor transition
    Area: graphene
    BibTeX:
    @article{Zhang2011f,
      author = {Zhang, C. X. and He, Chaoyu and Yu, Zhizhou and Zhang, K. W. and Sun, L. Z. and Zhong, Jianxin},
      title = {Transport Properties of Zigzag Graphene Nanoribbons Decorated by Carboxyl Group Chains},
      journal = {The Journal of Physical Chemistry C},
      year = {2011},
      volume = {115},
      number = {44},
      pages = {21893-21898},
      url = {http://pubs.acs.org/doi/abs/10.1021/jp204888q},
      doi = {http://dx.doi.org/10.1021/jp204888q}
    }
    
    Neha Tyagi & Anurag Srivastava Electronic Properties of AlN Nanocrystal: A First Principle Study 2011 AIP Conference Proceedings
    Vol. 1372(1)XVI NATIONAL SEMINAR ON FERROELECTRICS AND DIELECTRICS (NSFD-XVI), 259-262 
    DOI  
    Abstract: In the present paper, we have presented the analysis of electronic properties of 1-D AlN nanocrystal. The analysis has been made using the density functional theory based ATK-tool. The ground state total energy calculation approach of the system has been used through generalized gradient approximation (GGA) with revised Perdew-Burke-Ernzerhof (revPBE) type parameterization as exchange correlation functional. ATK has been applied to analyze the stability of Aluminium Nitride nanocrystal in its zinc blende (B3), rocksalt (B1) and CsCl (B2) type phases followed by electronic band structure and density of state computation and its analysis in comparison to its bulk crystal.
    Keywords: nanostructured materials; band structure; total energy systems; optimisation; ATK; Application
    Area: general
    BibTeX:
    @inproceedings{Tyagi2011,
      author = {Neha Tyagi and Anurag Srivastava},
      title = {Electronic Properties of AlN Nanocrystal: A First Principle Study},
      booktitle = {XVI NATIONAL SEMINAR ON FERROELECTRICS AND DIELECTRICS (NSFD-XVI)},
      journal = {AIP Conference Proceedings},
      publisher = {AIP},
      year = {2011},
      volume = {1372},
      number = {1},
      pages = {259-262},
      doi = {http://dx.doi.org/10.1063/1.3644454}
    }
    
    L.L. Song, X.H. Zheng, R.N. Wang, H. Hao & Z. Zeng Electron transport in metallic carbon nanotubes with multiple B and N dopants 2011 Physica E: Low-dimensional Systems and Nanostructures
    Vol. 44(2), 411 - 415 
    DOI  
    Abstract: We report a first-principles investigation of the effects of multiple B and N dopants on the electron transport in metallic carbon nanotubes. Firstly, the effects of two or more B atoms which are randomly or orderly distributed are investigated. Previous study has shown that single B or N dopant gives rise to a transmission valley either below or above the Fermi level. In contrast, we find that in the cases with two B dopants, the transmission valleys can still be observed but the position and the shape of valleys are generally highly dependent on the relative positions of the dopants due to the different interference between the dopants. However, when the nanotube is symmetrically doped with more B atoms along the circumference, the transmission spectra are much more simple. The conductance plateau around the Fermi level is lowered with the increasing dopants. Secondly, the influences of B and N atoms codoping on electronic transport are studied. When one B and one N atom are doped, the effects on the equilibrium conductance of this B-N pair are always negligible. The transmission patterns can be approximately considered as a superposition of the valleys induced by the individual dopants. Especially, when the B and N atoms are nearest neighbors, the valleys induced by the individual dopants may disappear. If more B and N dopants are doped, the corresponding transmission around the Fermi level is very sensitive to how these dopants are distributed. The equilibrium conductance can be suppressed from 2.0G0 to 0.3G0 in some cases.
    Keywords: ATK; Application; nanotube; doping;
    Area: nanotubes
    BibTeX:
    @article{Song2011,
      author = {L.L. Song and X.H. Zheng and R.N. Wang and H. Hao and Z. Zeng},
      title = {Electron transport in metallic carbon nanotubes with multiple B and N dopants},
      journal = {Physica E: Low-dimensional Systems and Nanostructures},
      year = {2011},
      volume = {44},
      number = {2},
      pages = {411 - 415},
      doi = {http://dx.doi.org/10.1016/j.physe.2011.09.009}
    }
    
    H.M. Liu, Z.Z. Zhao, N. Wang, C. Yu & J.W. Zhao Can the Transition from Tunneling to Hopping in Molecular Junctions Be Predicted by Theoretical Calculation? 2011 Journal of Computational Chemistry
    Vol. 32(8), 1687-1693 
    DOI  
    Abstract: The electron transport mechanism changes from tunneling to hopping as molecular length increases. To validate the theoretical simulation after the transition point and clarify influence of electronic structures on the transition, we calculated the conductance of a series of conjugated molecules by density functional theory together with the nonequilibrium Green's function. We found that the highest occupied molecular orbital energy level, transmission spectrum, and the reorganization energy are good indicators for the transition of the electron transport mechanism. The calculated resistances of short junctions (<50 Å, before the transition point) are consistent with the experimental result, following the tunneling mechanism. However, the theoretical predication failed for long molecules, indicating the limitation of the theoretical framework of elastic scattering when the electron transport mechanism changes to hopping.
    Keywords: electronic junctions; contact resistance; charge-transport; hole transport; wires; conductance; length; dependence; ATK; Application; molecular electronics; molecular junction; theoretical simulation; electron tunneling; electron hopping; reorganization energy
    Area: molecular electronics
    BibTeX:
    @article{Liu2011e,
      author = {Liu, H. M. and Zhao, Z. Z. and Wang, N. and Yu, C. and Zhao, J. W.},
      title = {Can the Transition from Tunneling to Hopping in Molecular Junctions Be Predicted by Theoretical Calculation?},
      journal = {Journal of Computational Chemistry},
      publisher = {Wiley-blackwell},
      year = {2011},
      volume = {32},
      number = {8},
      pages = {1687--1693},
      doi = {http://dx.doi.org/10.1002/jcc.21749}
    }
    
    Yi-Peng An & Zhong-Qin Yang Abnormal electronic transport and negative differential resistance of graphene nanoribbons with defects 2011 Applied Physics Letters
    Vol. 99(19), 192102 
    DOI URL 
    Abstract: Electronic transport properties of zigzag graphene nanoribbons (GNRs) with two kinds of triangular defects are explored by using an ab-initio method. At a certain bias, the current of the GNR with an upward-triangle defect can be surprisingly larger than that of the perfect GNR due to the defect-induced symmetry breaking and more conductive channels. Dissimilarly, if the orientation of the triangle is changed rightward, the current is depressed much and shows negative differential resistance behavior. Our findings indicate that defect designs can be an efficient way to tune the electronic transport of GNR nanodevices.
    Keywords: ab initio calculations; defect states; Fermi level; graphene; nanostructured materials; negative differential resistance; NDR; ATK; Application
    Area: graphene
    BibTeX:
    @article{An2011a,
      author = {Yi-Peng An and Zhong-Qin Yang},
      title = {Abnormal electronic transport and negative differential resistance of graphene nanoribbons with defects},
      journal = {Applied Physics Letters},
      publisher = {AIP},
      year = {2011},
      volume = {99},
      number = {19},
      pages = {192102},
      url = {http://link.aip.org/link/?APL/99/192102/1},
      doi = {http://dx.doi.org/10.1063/1.3660228}
    }
    
    Takahide Kubota, Masaaki Araidai, Shigemi Mizukami, Xianmin Zhang, Qinli Ma, Hiroshi Naganuma, Mikihiko Oogane, Yasuo Ando, Masaru Tsukada & Terunobu Miyazaki Composition dependence of magnetoresistance effect and its annealing endurance in tunnel junctions having Mn-Ga electrode with high perpendicular magnetic anisotropy 2011 Applied Physics Letters
    Vol. 99(19), 192509 
    DOI  
    Abstract: The composition dependence of the tunnel magnetoresistance (TMR) effect in Mn-Ga/MgO/CoFe magnetic tunnel junctions (MTJs) for Mn54Ga46, Mn62Ga38, and Mn71Ga29 (at. %) electrodes was investigated. An MTJ with a Mn62Ga38 electrode showed a maximum TMR ratio of 23% at 10 K and high annealing endurance up to 375°C. The bias voltage dependence of the TMR ratio was distinct among MTJs with different Mn-Ga compositions. Here, we discuss this dependence on the basis of the difference in the Delta1 band dispersions for Mn-Ga alloys calculated by first principles.
    Keywords: ab initio calculations; cobalt alloys; electrodes; gallium alloys; iron alloys; magnesium compounds; magnetic annealing; magnetic multilayers; manganese alloys; perpendicular magnetic anisotropy; tunnelling magnetoresistance; ATK; Application; spin; MTJ;
    Area: interfaces; spin; semi; nvm
    BibTeX:
    @article{Kubota2011,
      author = {Takahide Kubota and Masaaki Araidai and Shigemi Mizukami and Xianmin Zhang and Qinli Ma and Hiroshi Naganuma and Mikihiko Oogane and Yasuo Ando and Masaru Tsukada and Terunobu Miyazaki},
      title = {Composition dependence of magnetoresistance effect and its annealing endurance in tunnel junctions having Mn-Ga electrode with high perpendicular magnetic anisotropy},
      journal = {Applied Physics Letters},
      publisher = {AIP},
      year = {2011},
      volume = {99},
      number = {19},
      pages = {192509},
      doi = {http://dx.doi.org/10.1063/1.3659484}
    }
    
    A.H. Zhang, Y.H. Wu, S.H. Ke, Y.P. Feng & C. Zhang Bandgap engineering of zigzag graphene nanoribbons by manipulating edge states via defective boundaries 2011 Nanotechnology
    Vol. 22(43), 435702 
    DOI  
    Abstract: One of the most severe limits of graphene nanoribbons (GNRs) in future applications is that zigzag GNRs (ZGNRs) are gapless, so cannot be used in field effect transistors (FETs), and armchair GNR (AGNR) based FETs require atomically precise control of edges and width. Using the tight-binding approach and first principles method, we derived and proved a general boundary condition for the opening of a significant bandgap in ZGNRs with defective edge structures. The proposed semiconducting ZGNRs have some interesting properties one of which is that they can be embedded and integrated in a large piece of graphene without the need to completely cut them out. We also demonstrated a new type of high-performance all-ZGNR FET. Previous proposals of graphene FETs are all based on AGNRs.
    Keywords: bottom-up; initio; devices; metals; graphene nanoribbon; defects; ATK; Application; field-effect transistor; FET;
    Area: graphene
    BibTeX:
    @article{Zhang2011g,
      author = {Zhang, A. H. and Wu, Y. H. and Ke, S. H. and Feng, Y. P. and Zhang, C.},
      title = {Bandgap engineering of zigzag graphene nanoribbons by manipulating edge states via defective boundaries},
      journal = {Nanotechnology},
      publisher = {Iop Publishing Ltd},
      year = {2011},
      volume = {22},
      number = {43},
      pages = {435702},
      doi = {http://dx.doi.org/10.1088/0957-4484/22/43/435702}
    }
    
    S. Choudhary & S. Qureshi Theoretical study on the effect of vacancy defect reconstruction on electron transport in Si-C nanotubes 2011 Modern Physics Letters B
    Vol. 25(28), 2159-2170 
    DOI  
    Abstract: We investigate the effect of vacancy defect reconstruction on electron transport properties in a (4, 0) zigzag and (5, 5) armchair silicon-carbide nanotubes (SiCNTs) by applying self consistent non-equilibrium Green's function formalism in combination with the density-functional theory to a two probe molecular junction constructed from SiCNTs. The geometry optimization results show that single vacancies and di-vacancies in SiCNTs have different reconstructions. A single vacancy when optimized, reconstructs into a 5-1DB configuration in both zigzag and armchair SiCNTs, and a di-vacancy reconstructs into a 5-8-5 configuration in zigzag and into a 5-2DB configuration in armchair SiCNTs. Analysis of frontier molecular orbitals (FMO) and transmission spectrum show that the vacancy defect increases the band gap of (4, 0) metallic SiCNT and decreases the band gap of (5, 5) semiconducting SiCNT. Bias voltage dependent current characteristic show reduction in overall current in metallic SiCNT and an increase in overall current in semiconducting SiCNT.
    Keywords: silicon-carbide nanotubes; carbon nanotubes; ab-initio; vacancies; divacancies; defects; ATK; Application
    Area: nanotubes
    BibTeX:
    @article{Choudhary2011b,
      author = {Choudhary, S. and Qureshi, S.},
      title = {Theoretical study on the effect of vacancy defect reconstruction on electron transport in Si-C nanotubes},
      journal = {Modern Physics Letters B},
      publisher = {World Scientific Publ Co Pte Ltd},
      year = {2011},
      volume = {25},
      number = {28},
      pages = {2159--2170},
      doi = {http://dx.doi.org/10.1142/S0217984911027388}
    }
    
    Zhi-Qiang Fan, Zhen-Hua Zhang, Qiu Ming, Gui-Ping Tang & Ke-Qiu Chen First-principles study of repeated current switching in a bimolecular device 2012 Computational Materials Science
    Vol. 53(1), 294-297 
    DOI  
    Abstract: Using nonequilibrium Green's functions in combination with the first-principles density-functional theory, we investigate electronic transport properties of a bimolecular device consisting of two parallel placed phenalenyl molecules. When the two molecules get close enough, the currents of this bimolecular device could switch repeatedly by the mechanical strain. The deeper analysis indicates that the overlapping region size sensibly alters the coupling and charge transfer between the two parallel pi-conjugated molecules is a very important factor for this behavior.
    Keywords: nonequilibrium Green's functions; density-functional theory; bimolecular device; switching; ATK; Application
    Area: molecular electronics
    BibTeX:
    @article{Fan2012,
      author = {Fan, Zhi-Qiang and Zhang, Zhen-Hua and Ming, Qiu and Tang, Gui-Ping and Chen, Ke-Qiu},
      title = {First-principles study of repeated current switching in a bimolecular device},
      journal = {Computational Materials Science},
      year = {2012},
      volume = {53},
      number = {1},
      pages = {294--297},
      doi = {http://dx.doi.org/10.1016/j.commatsci.2011.08.004}
    }
    
    Neeraj K. Jaiswal & Pankaj Srivastava Structural stability and electronic properties of Ni-doped armchair graphene nanoribbons 2011 Solid State Communications
    Vol. 151(20), 1490-1495 
    DOI URL 
    Abstract: The size dependent electronic properties of armchair graphene nanoribbons (AGNR) with Ni doped atoms have been investigated using spin-unrestricted density functional theory. We predict antiferromagnetic (AFM) ground states for Ni-termination and one edge Ni-doping. The computed formation energy reveals that one edge Ni-terminated AGNR are energetically more favourable as compared to pristine ribbons. One edge substitutional doping is energetically more favourable as compared to centre doping by -1 eV whereas both edge doping is unfavourable. The bond length of substitutional Ni atoms is shorter than that of Ni adsorption in GNR, implying a stronger binding for substitutional Ni atoms. It is evident that binding energy is also affected by the coordination number of the foreign atom. The results show that Ni-interaction perturbs the electronic structure of the ribbons significantly, causing enhanced metallicity for all configurations irrespective of doping site. The band structures reveal the separation of spin up and down electronic states indicating towards the existence of spin polarized current in Ni-terminated and one edge doped ribbons. Our calculation predicts that AGNR containing Ni impurities can play an important role for the fabrication of spin filters and spintronic devices.
    Keywords: graphene nanoribbon; doping; electronic band structure; ATK; Application; spin; spin filter;
    Area: graphene; spin
    BibTeX:
    @article{Jaiswal2011a,
      author = {Jaiswal, Neeraj K. and Srivastava, Pankaj},
      title = {Structural stability and electronic properties of Ni-doped armchair graphene nanoribbons},
      journal = {Solid State Communications},
      year = {2011},
      volume = {151},
      number = {20},
      pages = {1490--1495},
      url = {http://www.sciencedirect.com/science/article/pii/S0038109811003334},
      doi = {http://dx.doi.org/10.1016/j.ssc.2011.06.032}
    }
    
    Y.W. Li, J.H. Yao, Z.G. Zou, J.W. Yang & S.R. Le Theoretical study of the electron transport through aromatic molecular wires with different levels of conjugation 2011 Computational and Theoretical Chemistry
    Vol. 976(1-3), 135-140 
    DOI URL 
    Abstract: The electron transport behaviors of three typical aromatic molecules (planar p-terphenyl, dibenzo[cd, Im]perylene, and dibenzo[bc, kl]coronene) with different levels of conjugation were studied theoretically using a combination of density functional theory and non-equilibrium Green's functions method. The results demonstrate that although the planar p-terphenyl is the least conjugated one among the three molecules, its conductance is significantly higher than those of dibenzo[cd, Im]perylene and dibenzo[bc, kl]coronene. The conductance of the three molecular wires decreases with an order of planar p-terphenyl > dibenzo[cd, Im]perylene > dibenzo[bc, kl]coronene, which is reverse to the order of the levels of conjugation of the three molecules. This unanticipated electron transport feature was analyzed from the transmission spectra and the molecular projected self-consistent Hamiltonian states of the three molecular wires under different applied bias. It is found that the orbital density at the molecule-electrode interface is the essential reason for generating this unanticipated electron transport behavior of the three aromatic molecular wires. The finding is expected to be helpful in designing and rationalization of high performance molecular wires for nanoscale applications.
    Keywords: molecular electronics; molecular conjugation; nonequilibrium Green's function; electronic transport; ATK; Application
    Area: molecular electronics
    BibTeX:
    @article{Li2011e,
      author = {Li, Y.W. and Yao, J.H. and Zou, Z.G. and Yang, J.W. and Le, S.R.},
      title = {Theoretical study of the electron transport through aromatic molecular wires with different levels of conjugation},
      journal = {Computational and Theoretical Chemistry},
      year = {2011},
      volume = {976},
      number = {1-3},
      pages = {135--140},
      url = {http://www.sciencedirect.com/science/article/pii/S2210271X11004385},
      doi = {http://dx.doi.org/10.1016/j.comptc.2011.08.014}
    }
    
    Qi Lin, Yu-Hang Chen, Jian-Bao Wu & Zong-Min Kong Effect of N-doping on band structure and transport property of zigzag graphene nanoribbons 2011 Acta Physica Sinica
    Vol. 60(9), 097103 
    URL 
    Abstract: The energy band structure, the transmission spectrum and the current-voltage characteristics of the N-doped zigzag graphene nanoribbons (z-GNRs) have been investigated by performing first-principles calculations. The results show the appearance of energy gap and a metal-semiconductor transition induced by N-doping of z-GNRs. With impurity concentration increasing, the current under the same bias decreases significantly, while the transmission coefficient near the Fermi surface decreases gradually. In addition, the length, the width and the N-doping position of z-GNR affect the transport property. Especially, the impurity concentration competes with the N-doping position in the influence on the transport property for narrow z-GNRs.
    Keywords: ATK; Application; graphene nanoribbons; N-doping; energy band structure; transport properties
    Area: graphene
    BibTeX:
    @article{Lin2011a,
      author = {Lin, Qi and Chen, Yu-Hang and Wu, Jian-Bao and Kong, Zong-Min},
      title = {Effect of N-doping on band structure and transport property of zigzag graphene nanoribbons},
      journal = {Acta Physica Sinica},
      year = {2011},
      volume = {60},
      number = {9},
      pages = {097103},
      url = {http://wulixb.iphy.ac.cn/cn/ch/common/view_abstract.aspx?flag=1&file_no=w20110982}
    }
    
    F Tavazza, L E Levine & A M Chaka Simulation approaches for studying the conductance behavior of gold nanowires during tensile deformation 2011 Modelling and Simulation in Materials Science and Engineering
    Vol. 19(7), 074001 
    DOI  
    Abstract: Under tensile deformation at 0 K, gold nanowires progressively thin through a series of metastable ordered structures down to a single atom chain. The conductances of these one-, two- or three-dimensional evolving self-ordered atomic structures are examined and used as test cases to explore several critical factors that must be considered when performing such calculations. These factors include the level of theory (tight binding, density functional theory, choice of basis set), the electrode geometry, and finally, the correspondence between conductance properties and the electronic band structure. Several example cases are explored.
    Keywords: ATK-SE; ATK; Application; gold nanowire; comparison; mechanical properties; deformation;
    Area: nanowires
    BibTeX:
    @article{Tavazza2011a,
      author = {F Tavazza and L E Levine and A M Chaka},
      title = {Simulation approaches for studying the conductance behavior of gold nanowires during tensile deformation},
      journal = {Modelling and Simulation in Materials Science and Engineering},
      year = {2011},
      volume = {19},
      number = {7},
      pages = {074001},
      doi = {http://dx.doi.org/10.1088/0965-0393/19/7/074001}
    }
    
    G.L. Zhang, H.L. Yuan, H. Zhang, Y. Shang & M. Sun Theoretical Studies on the Transport Property of Oligosilane with p-n Junction 2011 International Journal of Quantum Chemistry
    Vol. 111(15), 4214-4223 
    DOI  
    Abstract: The electron transport properties of a novel p-n junction nanowire caused by boron-doping and phosphorus-doping are investigated using density functional theory combined with the nonequilibrium Green's functions formalism. A satisfying rectification is observed. This is a reasonable result after the analysis of the molecular-projected self-consistent Hamitonian (MPSH) states, transmission spectra, the frontier orbitals, and the dipole moments. In contrast, the undoped chain has no rectification character. In addition, a negative differential resistance behavior is also observed at V = 1.8 similar to 2.2 V in the doped nanowire and it could be illustrated from the MPSH states and the transmission spectra.
    Keywords: electron propagator theory; molecular wires; silicon nanowires; conductance; diodes; formalism; surface; rectification; rectifier; oligomers; theoretical study; transport property; p-n junction; oligosilane; ATK; Application
    Area: nanowires
    BibTeX:
    @article{Zhang2011e,
      author = {Zhang, G. L. and Yuan, H. L. and Zhang, H. and Shang, Y. and Sun, M.},
      title = {Theoretical Studies on the Transport Property of Oligosilane with p-n Junction},
      journal = {International Journal of Quantum Chemistry},
      publisher = {Wiley-blackwell},
      year = {2011},
      volume = {111},
      number = {15},
      pages = {4214--4223},
      doi = {http://dx.doi.org/10.1002/qua.22723}
    }
    
    Haiying Liu, Genqin Li, Laibin Zhang, Jilai Li, Meishan Wang & Yuxiang Bu Electronic promotion effect of double proton transfer on conduction of DNA through improvement of transverse electronic communication of base pairs 2011 Journal of Chemical Physics
    Vol. 135(13), 134315 
    DOI  
    Abstract: The effect of double proton transfer (DPT) on charge migration of DNA was investigated by the nonequilibrium Green's function method combined with density functional theory. The results revealed that DPT not only lowers ionization potentials, but also improves the delocalization of the localized pi-orbitals at each base moiety through adjusting energy levels and spatial distributions of their molecular orbitals. Furthermore, DPT leads to both the strengthening of the second-order interactions of the Watson-Crick H-bond zones, and the promotion of the charge transfer transitions between two pairing bases in the UV absorption spectra. Electronic transport calculations indicated that DPT can improve the charge migration along the DNA duplex for specific sequences through enhancing transverse base-to-base electronic communication. This work will provide a new insight into the understanding of DNA charge conduction which can be electronically promoted or regulated by DPT.
    Keywords: bioelectric phenomena; density functional theory; dna; green's function methods; molecular biophysics; molecular configurations; ultraviolet spectra; density-functional theory; molecular-orbital methods; expanded guanine analogs; gaussian-basis sets; ab-initio; charge-transfer; excited-states; radical-cation; transport; adenine; ATK; Application
    Area: molecular electronics
    BibTeX:
    @article{Liu2011c,
      author = {Haiying Liu and Genqin Li and Laibin Zhang and Jilai Li and Meishan Wang and Yuxiang Bu},
      title = {Electronic promotion effect of double proton transfer on conduction of DNA through improvement of transverse electronic communication of base pairs},
      journal = {Journal of Chemical Physics},
      publisher = {AIP},
      year = {2011},
      volume = {135},
      number = {13},
      pages = {134315},
      doi = {http://dx.doi.org/10.1063/1.3646308}
    }
    
    Peng Zhao & Desheng Liu First-principles study of the electronic transport properties of a C131 -based molecular junction 2011 Solid State Communications
    Vol. 151(20), 1424 - 1427 
    DOI  
    Abstract: Using first-principles density functional theory and the non-equilibrium Green's function formalism, we have studied the electronic transport properties of the dumbbell-like fullerene dimer C131-based molecular junction. Our results show that the current-voltage curve displays an obvious negative differential resistance phenomenon in a certain bias voltage range. The negative differential resistance behavior can be understood in terms of the evolution of the transmission spectrum and the projected density of states with applied bias voltage. The present findings could be helpful for the application of the C131 molecule in the field of single molecular devices or nanometer electronics.
    Keywords: fullerene; ATK; Application; molecular junction; negative differential resistance; NDR;
    Area: fullerenes; molecular electronics
    BibTeX:
    @article{Zhao2011d,
      author = {Peng Zhao and Desheng Liu},
      title = {First-principles study of the electronic transport properties of a C131 -based molecular junction},
      journal = {Solid State Communications},
      year = {2011},
      volume = {151},
      number = {20},
      pages = {1424 - 1427},
      doi = {http://dx.doi.org/10.1016/j.ssc.2011.07.007}
    }
    
    Hong Seok Kang & Anup Pramanik The effect of doping on the energetics and quantum conductance in graphene nanoribbons with a metallocene adsorbate 2011 Journal of Chemical Physics
    Vol. 135(12), 124708 
    DOI  
    Abstract: Based on a PBE-D2 calculation that empirically includes van der Waals interactions to the standard GGA approximation of Perdew, Berke, and Ernzerhof, we have investigated the adsorption of ferrocene or ruthenocene on pristine and X-doped graphene (GrS) or graphene nanoribbons (GNRs), where X (=B or N) is a p-type or n-type heteroatom. First, we find that van der Waals interactions play a dominant role in the adsorption. Second, we find that metallocene adsorption on doped GNRs introduces different effects in the low-bias conductance, not far from the linear response regime, of GNRs depending upon the doping type. Adsorption on undoped or p-type GNRs brings about a slight reduction in conductance due to an introduction of quasi-bound states just below the Fermi level. No appreciable reduction is expected in n-type GNRs because those states are introduced far below the Fermi level.
    Keywords: adsorbed layers; adsorption; boron; bound states; doping; Fermi level; gradient methods; graphene; nanostructured materials; nitrogen; organometallic compounds; van der Waals forces; ATK; Application; ferrocene;
    Area: graphene
    BibTeX:
    @article{Kang2011,
      author = {Hong Seok Kang and Anup Pramanik},
      title = {The effect of doping on the energetics and quantum conductance in graphene nanoribbons with a metallocene adsorbate},
      journal = {Journal of Chemical Physics},
      publisher = {AIP},
      year = {2011},
      volume = {135},
      number = {12},
      pages = {124708},
      doi = {http://dx.doi.org/10.1063/1.3643337}
    }
    
    Jianhua Wu, Frank Hagelberg, Tandabany C. Dinadayalane, Danuta Leszczynska & Jerzy Leszczynski Do Stone-Wales Defects Alter the Magnetic and Transport Properties of Single-Walled Carbon Nanotubes? 2011 The Journal of Physical Chemistry C
    Vol. 115(45), 22232-22241 
    DOI  
    Abstract: Finite zigzag single-walled carbon nanotubes (SWCNTs) of some nanometers in length and modified by a topological defect of the Stone-Wales type were investigated by density functional theory (DFT) computation. Geometric changes of the regular hexagonal reference structures as well as alterations of their energetic, magnetic, and transport characteristics induced by the presence of the defect are recorded and discussed as a function of the tube length. SWCNT prototypes with hydrogen and fullerene hemisphere termination, and center as well as edge site defects are included in this study. The resulting four basic system types are characterized in terms of the Stone-Wales defect stabilization energy, as well as the energy gaps of the systems with and without Stone-Wales defects. While the magnetism of a zigzag SWCNT reacts sensitively to the nature and number of external adsorbates, it remains unaffected by the presence of Stone-Wales defects. However, the calculated current-voltage characteristic for a representative SWCNT with and without the defect, as well as the associated differential conductivity show a marked response to the defect for voltages exceeding about 1 V.
    Keywords: ATK; Application; nanotubes; Stone-Wales defects;
    Area: nanotubes
    BibTeX:
    @article{Wu2011b,
      author = {Wu, Jianhua and Hagelberg, Frank and Dinadayalane, Tandabany C. and Leszczynska, Danuta and Leszczynski, Jerzy},
      title = {Do Stone-Wales Defects Alter the Magnetic and Transport Properties of Single-Walled Carbon Nanotubes?},
      journal = {The Journal of Physical Chemistry C},
      year = {2011},
      volume = {115},
      number = {45},
      pages = {22232-22241},
      doi = {http://dx.doi.org/10.1021/jp207510n}
    }
    
    J.H. Yao, Y.W. Li, Z.G. Zou, J.W. Yang & Z.L. Yin First principles study of the electron transport through cis-polyacetylene based molecular wires 2011 Physica B: Condensed Matter
    Vol. 406(20), 3969-3974 
    DOI  
    Abstract: The electron transport properties of cis-polyacetylene and cis-polyacetylene based molecular wires (oligo(cyclopentadiene), oligo(pyrrole), and oligo(furan)) have been studied theoretically using a combination of density-functional theory and non-equilibrium Green's functions method. The results demonstrate that the introduction of bridging group X (X=CH(2), NH, and O) in cis-polyacetylene has a profound effect on the electron transport behavior of the molecules. The conductance of the four molecular wires decreases in the order of polyacetylene > oligo(cyclopentadiene) > oligo(furan) > oligo(pyrrole). In particular, the conductances of oligo(furan) and oligo(pyrrole) are much lower than those of polyacetylene and oligo(cyclopentadiene). The mechanism of this difference of electron transport properties of these four molecular systems is analyzed in terms of their geometric structures, electronic structures, transmission spectra, and spatial distribution of frontier orbitals. It is found that the energy levels of frontier molecular orbitals and the evolution of spatial distribution of frontier molecular orbitals with the applied bias are the essential reason for generating this difference of electron transport behaviors of the four molecular systems.
    Keywords: junction conductance; band-gaps; copolymers; dependence; resistance; behavior; devices; state; field; ATK; Application; molecular electronics; molecular wires; non-equilibrium Green's function; electron transport
    Area: molecular electronics
    BibTeX:
    @article{Yao2011,
      author = {Yao, J. H. and Li, Y. W. and Zou, Z. G. and Yang, J. W. and Yin, Z. L.},
      title = {First principles study of the electron transport through cis-polyacetylene based molecular wires},
      journal = {Physica B: Condensed Matter},
      publisher = {Elsevier Science Bv},
      year = {2011},
      volume = {406},
      number = {20},
      pages = {3969--3974},
      doi = {http://dx.doi.org/10.1016/j.physb.2011.07.040}
    }
    
    S.D. Yuan, S.Y. Wang, Q.B. Mei, Q.D. Ling, L.H. Wang & W. Huang First-Principles Study of Rectification in Bis-2-(5-ethynylthienyl)ethyne Molecular Junctions 2011 Journal of Physical Chemistry A
    Vol. 115(32), 9033-9042 
    DOI  
    Abstract: Using density functional theory (DFT) combined with the first-principles nonequilibrium Green's function (NEGF), we investigated the electron-transport properties and rectifying behaviors of several molecular junctions based on the bis-2-(5-ethynylthienyl)ethyne (BETE) molecule. To examine the roles of different rectification factors, asymmetric electrode molecule contacts and donor-acceptor substituent groups were introduced into the BETE-based molecular junction. The asymmetric current-voltage characteristics were obtained for the molecular junctions containing asymmetric contacts and donor-acceptor groups. In our models, the computed rectification ratios show that the mode of electrode-molecule contacts plays a crucial role in rectification and that the rectifying effect is not enhanced significantly by introducing the additional donor-acceptor components for the molecular rectifier with asymmetric electrode molecule contacts. The current-voltage characteristics and rectifying behaviors are discussed in terms of transmission spectra, molecular projected self-consistent Hamiltonian (MPSH) states, and energy levels of MPSH states.
    Keywords: self-assembled monolayers; electronic transport; anchoring group; conductance; density; rectifiers; devices; diodes; substituents; contacts; ATK; Application; molecular electronics
    Area: molecular electronics
    BibTeX:
    @article{Yuan2011a,
      author = {Yuan, S. D. and Wang, S. Y. and Mei, Q. B. and Ling, Q. D. and Wang, L. H. and Huang, W.},
      title = {First-Principles Study of Rectification in Bis-2-(5-ethynylthienyl)ethyne Molecular Junctions},
      journal = {Journal of Physical Chemistry A},
      publisher = {Amer Chemical Soc},
      year = {2011},
      volume = {115},
      number = {32},
      pages = {9033--9042},
      doi = {http://dx.doi.org/10.1021/jp204161z}
    }
    
    Anirban Bandyopadhyay & Somobrata Acharya A 16-bit parallel processing in a molecular assembly 2008 Proceedings of the National Academy of Sciences
    Vol. 105(10), 3668-3672 
    DOI  
    Abstract: A machine assembly consisting of 17 identical molecules of 2,3,5,6-tetramethyl-1-4-benzoquinone (DRQ) executes 16 instructions at a time. A single DRQ is positioned at the center of a circular ring formed by 16 other DRQs, controlling their operation in parallel through hydrogen-bond channels. Each molecule is a logic machine and generates four instructions by rotating its alkyl groups. A single instruction executed by a scanning tunneling microscope tip on the central molecule can change decisions of 16 machines simultaneously, in four billion (4^16) ways. This parallel communication represents a significant conceptual advance relative to today's fastest processors, which execute only one instruction at a time.
    Keywords: ATK; Application; molecular switch;
    Area: molecular electronics
    BibTeX:
    @article{Bandyopadhyay2008,
      author = {Bandyopadhyay, Anirban and Acharya, Somobrata},
      title = {A 16-bit parallel processing in a molecular assembly},
      journal = {Proceedings of the National Academy of Sciences},
      year = {2008},
      volume = {105},
      number = {10},
      pages = {3668--3672},
      doi = {http://dx.doi.org/10.1073/pnas.0703105105}
    }
    
    Anirban Bandyopadhyay, Ranjit Pati, Satyajit Sahu, Ferdinand Peper & Daisuke Fujita Massively parallel computing on an organic molecular layer 2010 Nature Physics
    Vol. 6(5), 369-375 
    DOI  
    Abstract: Modern computers operate at enormous speeds - capable of executing in excess of 10^13 instructions per second - but their sequential approach to processing, by which logical operations are performed one after another, has remained unchanged since the 1950s. In contrast, although individual neurons of the human brain fire at around just 10^3 times per second, the simultaneous collective action of millions of neurons enables them to complete certain tasks more efficiently than even the fastest supercomputer. Here we demonstrate an assembly of molecular switches that simultaneously interact to perform a variety of computational tasks including conventional digital logic, calculating Voronoi diagrams, and simulating natural phenomena such as heat diffusion and cancer growth. As well as representing a conceptual shift from serial-processing with static architectures, our parallel, dynamically reconfigurable approach could provide a means to solve otherwise intractable computational problems.
    Keywords: ATK; Application; molecular switch;
    Area: molecular electronics
    BibTeX:
    @article{Bandyopadhyay2010,
      author = {Bandyopadhyay, Anirban and Pati, Ranjit and Sahu, Satyajit and Peper, Ferdinand and Fujita, Daisuke},
      title = {Massively parallel computing on an organic molecular layer},
      journal = {Nature Physics},
      publisher = {Nature Publishing Group},
      year = {2010},
      volume = {6},
      number = {5},
      pages = {369--375},
      doi = {http://dx.doi.org/10.1038/nphys1636}
    }
    
    Mohammad Khazaei, Yunye Liang, Mohammad Saeed Bahramy, Fabio Pichierri, Keivan Esfarjani & Yoshiyuki Kawazoe High-pressure phases of hydrogen cyanide: formation of hydrogenated carbon nitride polymers and layers and their electronic properties 2011 Journal of Physics: Condensed Matter
    Vol. 23(40), 405403 
    DOI  
    Abstract: We have performed a set of first-principles simulations to consider the possible phase transitions in molecular crystals of HCN under high pressure. Our calculations reveal several transition paths from the orthorhombic phase to tetragonal and then to triclinic phases. The transitions from the orthorhombic to the tetragonal phases are of the second order, whereas those from the tetragonal to the triclinic phases turn out to be of the first-order type and characterized by an abrupt decrease in volume. Our calculations show that, by adjustment of the temperature and pressure of the HCN molecular crystal, novel layered and polymeric crystals with insulating, semiconducting or metallic properties can be found. Based on our simulation results, two different crystal formation mechanisms are deduced. The stabilities of the predicted structures at ambient pressure are further assessed by performing phonon or MD simulations. In addition, the electron transport properties of the predicted polymers are obtained using the non-equilibrium Green's function technique combined with density functional theory. The results show that the polymers have metallic-like I-V characteristics.
    Keywords: molecular electronics; molecular crystal; phase transition; density-functional theory; computer experiments; (hcn)(n) clusters; classical fluids; solid hcn; crystals; energy; transformation; computations; spectroscopy; ATK; Application
    Area: molecular electronics
    BibTeX:
    @article{Khazaei2011,
      author = {Mohammad Khazaei and Yunye Liang and Mohammad Saeed Bahramy and Fabio Pichierri and Keivan Esfarjani and Yoshiyuki Kawazoe},
      title = {High-pressure phases of hydrogen cyanide: formation of hydrogenated carbon nitride polymers and layers and their electronic properties},
      journal = {Journal of Physics: Condensed Matter},
      year = {2011},
      volume = {23},
      number = {40},
      pages = {405403},
      doi = {http://dx.doi.org/10.1088/0953-8984/23/40/405403}
    }
    
    Xiaojian Tan, Huijun Liu, Yanwei Wen, Hongyan Lv, Lu Pan, Jing Shi & Xinfen