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    Yongqing Cai, Aihua Zhang, Yuan Ping Feng & Chun Zhang Switching and rectification of a single light-sensitive diarylethene molecule sandwiched between graphene nanoribbons

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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;
    Area: graphene
    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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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
    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

    [Abstract] [BibTeX]

    		 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}
}
    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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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: density functional theory, electronic structure, graphene nanoribbons, mechanical properties, ATK, Application
    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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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; transition metals; graphane; 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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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?

    [Abstract] [BibTeX]

    		 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 angstrom A, 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}
}
    Yipeng An & Zhongqin Yang Abnormal electronic transport and negative differential resistance of graphene nanoribbons with defects

    [Abstract] [BibTeX]

    		 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 = {Yipeng An and Zhongqin 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

    [Abstract] [BibTeX]

    		 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
    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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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}
}
    Matsuura Yukihito Spin transport in bimetallic pentalene complexes

    [Abstract] [BibTeX]

    		 2011 Solid State Communications
    Vol. 151(24), 1877-1880     		 DOI URL 
    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
    Area: molecular electronics; spin
    BibTeX: 
    @article{Yukihito2011,
  author = {Yukihito, Matsuura},
  title = {Spin transport in bimetallic pentalene complexes},
  journal = {Solid State Communications},
  year = {2011},
  volume = {151},
  number = {24},
  pages = {1877--1880},
  url = {http://www.sciencedirect.com/science/article/pii/S0038109811005278},
  doi = {http://dx.doi.org/10.1016/j.ssc.2011.10.001}
}
    G.L. Zhang, H.L. Yuan, H. Zhang, Y. Shang & M. Sun Theoretical Studies on the Transport Property of Oligosilane with p-n Junction

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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

    [BibTeX]

    		 2011 Journal of Chemical Physics
    Vol. 135(12), 124708     		 DOI  
    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?

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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

    [Abstract] [BibTeX]

    		 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 & Xinfeng Tang Thermoelectric Properties of Ultra-Small Single-Wall Carbon Nanotubes

    [Abstract] [BibTeX]

    		 2011 The Journal of Physical Chemistry C
    Vol. 115, 21996     		 DOI  
    Abstract: The electronic transports of three kinds of ultra-small single-wall carbon nanotubes are studied by using nonequilibrium Green's function method. It is found that the transmission function displays a clear stepwise structure that gives the number of electron channels. The calculated power factor (S^2G ) of these nanotubes can be optimized to much higher values in a wide temperature range. Using nonequilibrium molecule dynamics simulations, the lattice thermal conductance of these nanotubes are predicated with quantum correction. Our calculations indicate that the (4,2) tube have relatively higher room temperature figure of merit (ZT value) compared with those of the (5,0) and (3,3) tubes. Moreover, the thermoelectric performance of these nanotubes can be greatly enhanced by surface design, formation of bundles, and increasing the tube length, etc which significantly reduce the phonon and/or electron derived thermal conductance.
    Keywords: nanotubes; thermoelectricity; figure of merit; ZT; ATK; Application
    Area: nanotubes
    BibTeX: 
    @article{Tan2011,
  author = {Tan, Xiaojian and Liu, Huijun and Wen, Yanwei and Lv, Hongyan and Pan, Lu and Shi, Jing and Tang, Xinfeng},
  title = {Thermoelectric Properties of Ultra-Small Single-Wall Carbon Nanotubes},
  journal = {The Journal of Physical Chemistry C},
  year = {2011},
  volume = {115},
  pages = {21996},
  doi = {http://dx.doi.org/10.1021/jp205333m}
}
    Minggang Zeng, Yuanping Feng & Gengchiau Liang Thermally induced currents in graphene-based heterostructure

    [Abstract] [BibTeX]

    		 2011 Applied Physics Letters
    Vol. 99(12), 123114     		 DOI  
    Abstract: We investigate thermally induced currents in a zigzag graphene nanoribbon (ZGNR) heterostructure, consisting of hydrogen-terminated ZGNR (ZGNR-H) and oxygen-terminated ZGNR (ZGNR-O), under different electronic and magnetic states. Compared to a pure ZGNR-H system, the heterostructure displays a considerably larger thermally induced current due to its asymmetric transmission spectrum. Moreover, the magnetized ZGNR-H/ZGNR-O shows spin filter and magnetoresistance effects, suggesting potential applications of the ZGNR-H/ZGNR-O heterostructures in thermoelectric and spintronics devices.
    Keywords: graphene nanoribbon; heterostructure; magnetoelectronics; magnetoresistance; nanostructured materials; thermal conductivity; ATK; Application; field-effect transistor
    Area: graphene
    BibTeX: 
    @article{Zeng2011f,
  author = {Minggang Zeng and Yuanping Feng and Gengchiau Liang},
  title = {Thermally induced currents in graphene-based heterostructure},
  journal = {Applied Physics Letters},
  publisher = {AIP},
  year = {2011},
  volume = {99},
  number = {12},
  pages = {123114},
  doi = {http://dx.doi.org/10.1063/1.3641478}
}
    Z.Q. Fan, Z.H. Zhang, M. Qiu & G.P. Tang Rectifying performance and reversible conductance switching of single-polyaniline devices

    [Abstract] [BibTeX]

    		 2011 Physics Letters A
    Vol. 375(37), 3314-3318     		 DOI  
    Abstract: By applying nonequilibrium Green's functions in combination with the density-functional theory, we investigate the transport properties of single-polyaniline molecular devices. The results show that these devices can perform a reversible switching behavior by oxidation/reduction, which agrees well with the experimental results. In addition, a rectifying performance is only found in the device on emeraldine base. Detailed analyses of the charge transfer and the transmission spectra of the devices reveal the mechanism of these behaviors.
    Keywords: transport properties; molecular electronics; ATK; Application; conductance switching;
    Area: molecular electronics
    BibTeX: 
    @article{Fan2011a,
  author = {Fan, Z. Q. and Zhang, Z. H. and Qiu, M. and Tang, G. P.},
  title = {Rectifying performance and reversible conductance switching of single-polyaniline devices},
  journal = {Physics Letters A},
  publisher = {Elsevier Science Bv},
  year = {2011},
  volume = {375},
  number = {37},
  pages = {3314--3318},
  doi = {http://dx.doi.org/10.1016/j.physleta.2011.07.023}
}
    Changfeng Fang, Bin Cui, Yuqing Xu, Guomin Ji, Desheng Liu & Shijie Xie Electronic transport properties of carbon chains between Au and Ag electrodes: A first-principles study

    [Abstract] [BibTeX]

    		 2011 Physics Letters A
    Vol. 375(41), 3618-3623     		 DOI  
    Abstract: We report first-principles calculations of the current-voltage characteristic and the conductance of carbon-based molecular wires with different length capped with sulfur ends between two metallic electrodes made of different metals. The optimized molecular structure of carbon chain in the junction is presented on the structure of polyyne. The conductance of the polyyne wires shows oscillatory behavior depending on the number of carbon atoms (triple bonds). Current rectification is found and rectification direction presents inversion with the odd and even number of carbon atoms.
    Keywords: Electronic transport; Rectification; Asymmetric electrode; Non-equilibrium Green's function; molecular electronics; ATK; Application
    Area: molecular electronics
    BibTeX: 
    @article{Fang2011a,
  author = {Fang, Changfeng and Cui, Bin and Xu, Yuqing and Ji, Guomin and Liu, Desheng and Xie, Shijie},
  title = {Electronic transport properties of carbon chains between Au and Ag electrodes: A first-principles study},
  journal = {Physics Letters A},
  year = {2011},
  volume = {375},
  number = {41},
  pages = {3618--3623},
  doi = {http://dx.doi.org/10.1016/j.physleta.2011.08.032}
}
    J. Puigmarti-Luis, A. Minoia, S.B. Lei, V. Geskin, B. Li, R. Lazzaroni, S. De Feyter & D.B. Amabilino Self-assembly of supramolecular wires and cross-junctions and efficient electron tunnelling across them

    [Abstract] [BibTeX]

    		 2011 Chemical Science
    Vol. 2(10), 1945-1951     		 DOI  
    Abstract: The self-assembly of molecules incorporating pi-electron rich units into supramolecular wires is shown by scanning tunnelling microscopy (STM) at a graphite-liquid interface. Hydrogen bonds between the side chains of these molecules ensure a face-to-face contact between the functional moieties, which would otherwise lie flat on the surface if the amide groups affording this effect were absent. The organisation in the wires also depends critically on the constitution of the molecule: The cis and trans isomers show ordered and disordered spacing between wires, respectively. The supramolecular wires formed by the cis isomer form crossed architectures, with multilayers of the linear structures being formed. Study of the junction points between the fibres by scanning tunnelling spectroscopy shows that tunnelling electrons are transported efficiently, practically with the same probability as through a single wire. Molecular modelling is used to determine how the pi-electron rich units within two crossing wires organise at the crossing. Based on those structural data, the electron tunnelling probability between tip and substrate is then calculated; it shows that electron transmission can indeed take place at the crossing. This result implies that supramolecular fibres can be used as wires in order to build integrated circuits by bottom-up construction from the molecule scale.
    Keywords: liquid-solid interface; tetrathiafulvalene derivatives; organic-molecules; building-blocks; fibers; transport; surfaces; devices; nanostructures; microscopy; ATK; Application; experimental comparison
    Area: molecular electronics
    BibTeX: 
    @article{PuigmartiLuis2011,
  author = {Puigmarti-Luis, J. and Minoia, A. and Lei, S. B. and Geskin, V. and Li, B. and Lazzaroni, R. and De Feyter, S. and Amabilino, D. B.},
  title = {Self-assembly of supramolecular wires and cross-junctions and efficient electron tunnelling across them},
  journal = {Chemical Science},
  publisher = {Royal Soc Chemistry},
  year = {2011},
  volume = {2},
  number = {10},
  pages = {1945--1951},
  doi = {http://dx.doi.org/10.1039/c1sc00330e}
}
    F. Tavazza, D.T. Smith, L.E. Levine, J.R. Pratt & A.M. Chaka Electron Transport in Gold Nanowires: Stable 1-, 2- and 3-Dimensional Atomic Structures and Noninteger Conduction States

    [Abstract] [BibTeX]

    		 2011 Phys. Rev. Lett.
    Vol. 107(12), 126802-     		 DOI  
    Abstract: Experimental conductivity measurements made during highly stable tensile deformation of Au nanowires show a rich variety of behaviors, including noninteger quantum conductance plateaus, transitions, and slopes. Using tight binding conductance calculations on simulated nanowires previously deformed using density functional theory, we demonstrate that all of these phenomena arise from structural transitions between deeply metastable ordered atomic configurations that self-organize during tensile deformation.
    Keywords: gold nanowire; ATK; ATK-SE; Application; experimental comparison; quantum conductance; strain
    Area: nanowires
    BibTeX: 
    @article{Tavazza2011,
  author = {Tavazza, F. and Smith, D. T. and Levine, L. E. and Pratt, J. R. and Chaka, A. M.},
  title = {Electron Transport in Gold Nanowires: Stable 1-, 2- and 3-Dimensional Atomic Structures and Noninteger Conduction States},
  journal = {Phys. Rev. Lett.},
  publisher = {American Physical Society},
  year = {2011},
  volume = {107},
  number = {12},
  pages = {126802--},
  doi = {http://dx.doi.org/10.1103/PhysRevLett.107.126802}
}
    Cai-Juan Xia, De-Sheng Liu & Ying-Tang Zhang Electronic Transport Properties of a Naphthopyran-Based Optical Molecular Switch: an ab initio Study

    [Abstract] [BibTeX]

    		 2011 Chinese Physics Letters
    Vol. 28(9), 093102     		 DOI  
    Abstract: The electronic transport properties of a naphthopyran-based molecular optical switch are investigated by using the nonequilibrium Green's function formalism combined with first-principles density functional theory. The molecule that comprises the switch can convert between its open and closed forms upon photoexcitation. Theoretical results show that the current through the open form is significantly larger than that through the closed form, which is different from other optical switches based on ring-opening reactions of the molecular bridge. The maximum on-off ratio (about 90) can be obtained at 1.4 V. The physical origin of the switching behavior is interpreted based on the spatial distributions of molecular orbitals and the HOMO-LUMO gap. Our result shows that the naphthopyran-based molecule is a good candidate for optical molecular switches and will be useful in the near future.
    Keywords: ATK; Application; molecular optical switch;
    Area: molecular electronics
    BibTeX: 
    @article{Xia2011h,
  author = {Xia, Cai-Juan and Liu, De-Sheng and Zhang, Ying-Tang},
  title = {Electronic Transport Properties of a Naphthopyran-Based Optical Molecular Switch: an ab initio Study},
  journal = {Chinese Physics Letters},
  year = {2011},
  volume = {28},
  number = {9},
  pages = {093102},
  doi = {http://dx.doi.org/10.1088/0256-307X/28/9/093102}
}
    J. Zeng, K.Q. Chen, J. He, X.J. Zhang & W.P. Hu Rectifying and successive switch behaviors induced by weak intermolecular interaction

    [Abstract] [BibTeX]

    		 2011 Organic Electronics
    Vol. 12(10), 1606-1611     		 DOI  
    Abstract: By applying nonequilibrium Green's functions in combination with density-function theory, we investigate the effect of the weak intermolecular interaction on electronic transport properties in a bilayer graphene nanoribbon device. The results show that a successive switch behavior can be realized by adjusting the weak pi-pi interaction between two graphene nanoribbon molecules. Moreover, rectifying behavior can be observed in such systems. The mechanisms for these phenomena are suggested.
    Keywords: electronic transport; graphene; junctions; conductance; electronic transport in nanoscale materials and structures; switch behaviors; current rectification; weak intermolecular interaction; ATK; Application
    Area: graphene
    BibTeX: 
    @article{Zeng2011e,
  author = {Zeng, J. and Chen, K. Q. and He, J. and Zhang, X. J. and Hu, W. P.},
  title = {Rectifying and successive switch behaviors induced by weak intermolecular interaction},
  journal = {Organic Electronics},
  publisher = {Elsevier Science Bv},
  year = {2011},
  volume = {12},
  number = {10},
  pages = {1606--1611},
  doi = {http://dx.doi.org/10.1016/j.orgel.2011.06.010}
}
    X.J. Zhang, K.Q. Chen, L.M. Tang & M.Q. Long Electronic transport properties on V-shaped-notched zigzag graphene nanoribbons junctions

    [Abstract] [BibTeX]

    		 2011 Physics Letters A
    Vol. 375(37), 3319-3324     		 DOI  
    Abstract: Using nonequilibrium Green's functions in combination with the density functional theory, the spin-dependent electronic transport properties on V-shaped notched zigzag-edged graphene nanoribbons junctions have been calculated. The results show that the electronic transport properties are strongly depending on the type of notch and the symmetry of ribbon. The spin-filter phenomenon and negative differential resistance behaviors can be observed. A physical analysis of these results is given.
    Keywords: graphene nanoribbons; v-shaped notch; first-principles; electronic transport properties; spin filter; ATK; Application
    Area: graphene; spin
    BibTeX: 
    @article{Zhang2011d,
  author = {Zhang, X. J. and Chen, K. Q. and Tang, L. M. and Long, M. Q.},
  title = {Electronic transport properties on V-shaped-notched zigzag graphene nanoribbons junctions},
  journal = {Physics Letters A},
  publisher = {Elsevier Science Bv},
  year = {2011},
  volume = {375},
  number = {37},
  pages = {3319--3324},
  doi = {http://dx.doi.org/10.1016/j.physleta.2011.07.029}
}
    K.G. Zhou, Y.H. Zhang, L.J. Wang, K.F. Xie, Y.Q. Xiong, H.L. Zhang & C.W. Wang Can azulene-like molecules function as substitution-free molecular rectifiers?

    [Abstract] [BibTeX]

    		 2011 Physical Chemistry Chemical Physics
    Vol. 13(35), 15882-15890     		 DOI  
    Abstract: The feasibility of employing azulene-like molecules as a new type of high performance substitution-free molecular rectifier has been explored using NEGF-DFT calculation. The electronic transport behaviors of metal-molecule-metal junctions consisting of various azulene-like dithiol molecules are investigated, which reveals that the azulene-like molecules exhibit high conductance and bias-dependent rectification effects. Among all the substitution-free azulene-like structures, cyclohepta[b]cyclopenta[g]naphthalene exhibits the highest rectification ratio, revealing that the all fused aromatic ring structure and an appropriate separation between the pentagon and heptagon rings are essential for achieving both high conductance and high rectification ratio. The rectification ratio can be increased by substituting the pentagon ring with electron withdrawing group and/or the heptagon ring with electron donating groups. Further increase of the rectification ratio may also be obtained by lithium adsorption on the pentagon ring. This work reveals that azulene-like molecules may be used as a new class of highly conductive unimolecular rectifiers.
    Keywords: quantum transport-properties; self-assembled monolayers; ab-initio; gold electrodes; rectification; ATK; Application
    Area: molecular electronics
    BibTeX: 
    @article{Zhou2011a,
  author = {Zhou, K. G. and Zhang, Y. H. and Wang, L. J. and Xie, K. F. and Xiong, Y. Q. and Zhang, H. L. and Wang, C. W.},
  title = {Can azulene-like molecules function as substitution-free molecular rectifiers?},
  journal = {Physical Chemistry Chemical Physics},
  publisher = {Royal Soc Chemistry},
  year = {2011},
  volume = {13},
  number = {35},
  pages = {15882--15890},
  doi = {http://dx.doi.org/10.1039/c0cp02693j}
}
    I.B.M. Dason, V.R. Kumar & A.A. Kirubaraj Realization of Magnetic RAM using Magnetic Tunneling Junction in atomic level

    [Abstract] [BibTeX]

    		 2011
    Vol. 4Electronics Computer Technology (ICECT), 2011 3rd International Conference on, 397 -401     		 DOI  
    Abstract: Magnetic RAM (MRAM) is the non-volatile memory device with excellent endurance. Magnetic Tunneling Junction (MTJ) is the basic building block of the MRAM which is used to store information extracting the two-valued resistance property. With the discovery of Giant Magneto Resistance effect (GMR) and Tunnel Magneto Resistance effect (TMR) phenomenon in the magnetic multilayer of MTJ, the difference between the two resistances is distinct. Writing in MTJ can be carried with superior speed, low power using Spin Transfer Torque (STT) writing technique. The parallel and anti-parallel configurations of the MTJ can be carried out by manipulating the spin of the electrons of the magnetic multilayer. In this paper, we have modelled the Fe-MgO-Fe MTJ in atomic level using the software Atomistix ToolKit (ATK) Virtual NanoLab (VNL) 2008.10. We have analysed the V-I characteristics of the MTJ for the various bias voltages and have obtained the resistance of 5.2 M Ohm and 55.7 M Ohm for the parallel and anti-parallel configurations respectively. This difference in the two resistances holds good to differentiate the data "0" or "1" stored in the MTJ. The TMR thus calculated is around 950%. Higher the TMR ratio lower is the Resistance Area (RA) product.
    Keywords: Atomistix ToolKit software; Virtual NanoLab 2008.10; atomic level; giant magneto resistance effect; information extraction; magnetic RAM; magnetic multilayer; magnetic tunneling junction; nonvolatile memory device; resistance area product; spin transfer torque writing technique; tunnel magneto resistance effect; two-valued resistance property; MRAM devices; giant magnetoresistance; information retrieval; magnetic multilayers; tunnelling magnetoresistance; virtual instrumentation; MTJ; spin; ATK; Application
    Area: interfaces; spin
    BibTeX: 
    @inproceedings{5941929,
  author = {Dason, I.B.M. and Kumar, V.R. and Kirubaraj, A.A.},
  title = {Realization of Magnetic RAM using Magnetic Tunneling Junction in atomic level},
  booktitle = {Electronics Computer Technology (ICECT), 2011 3rd International Conference on},
  year = {2011},
  volume = {4},
  pages = {397 -401},
  doi = {http://dx.doi.org/10.1109/ICECTECH.2011.5941929}
}
    H. Medina, Y.C. Lin, D. Obergfell & P.W. Chiu Tuning of Charge Densities in Graphene by Molecule Doping

    [Abstract] [BibTeX]

    		 2011 Advanced Functional Materials
    Vol. 21(14), 2687-2692     		 DOI  
    Abstract: The tuning of carrier concentrations in graphene is at the heart of graphene-based nanoelectronic and optoelectronic applications. Molecular doping, that is, taking charges from the adsorbed molecules, shows promise as a means by which to change carrier density in graphene while retaining relative high mobility. However, poor control over doping concentrations is a major obstacle to practical applications. Here, we show that lattice disorders induced by plasma exposure can be used as anchor groups. These groups serve as centers of molecule adsorption and facilitate orbital overlap between graphene and adsorbates (melamine), thus allowing for selective and tunable doping. The carrier concentration revealed by Raman shift can be progressively adjusted up to 1.4 x 10(13) cm(-2), depending on the coverage of melamine molecules and doping temperature. The electronic band structures of the graphene melamine complex were calculated using density functional theory for adsorption over ideal graphene and over non-ideal graphene with Stone-Wales (5-7-7-5) defects. It is shown that charge transfer for adsorption on ideal graphene is negligible, while adsorption on graphene with Stone-Wales defects results in weak hole doping, which is consistent with the progressive increase of carrier density with increasing melamine coverage.
    Keywords: field-effect transistors; raman-scattering; defects; films; gas; graphene; doping; experimental comparison; ATK; Application
    Area: graphene
    BibTeX: 
    @article{Medina2011,
  author = {Medina, H. and Lin, Y. C. and Obergfell, D. and Chiu, P. W.},
  title = {Tuning of Charge Densities in Graphene by Molecule Doping},
  journal = {Advanced Functional Materials},
  publisher = {Wiley-blackwell},
  year = {2011},
  volume = {21},
  number = {14},
  pages = {2687--2692},
  doi = {http://dx.doi.org/10.1002/adfm.201100401}
}
    Anurag Srivastava, Neha Tyagi & R.K. Singh First Principle Study of Structural and Electronic Properties of Silicon Nanowires

    [Abstract] [BibTeX]

    		 2011 Journal of Computational and Theoretical Nanoscience
    Vol. 8(8), 1418-1423     		 DOI  
    Abstract: Ab-initio self-consistent study of Silicon nanostructures have been performed in various atomic configurations using atomistix tool. Atomic geometries of Silicon nanowires with the lowest energy have been analysed to confirm their stability. Out of the six atomic geometries of Silicon nanowire taken into consideration (linear, zigzag, ladder, square, triangular and dumbbell), the two-atom zigzag shaped geometry with the lowest total energy and highest binding energy has been confirmed as the most stable structure. The study has been made using GGA exchange correlation with revised Perdew Burke and Ernzerhoff type parameterization. The calculated lattice parameter of bulk silicon is in good agreement with its experimental counterpart. The electronic band structures, density of states and bulk modulus for different atomic geometries of Si nanowires have also been analysed.
    Keywords: silicon nanowires, stability, electronic properties, bulk modulus, ab initio, ATK, Application
    Area: nanowires
    BibTeX: 
    @article{Srivastava2011a,
  author = {Srivastava, Anurag and Tyagi, Neha and Singh, R.K.},
  title = {First Principle Study of Structural and Electronic Properties of Silicon Nanowires},
  journal = {Journal of Computational and Theoretical Nanoscience},
  year = {2011},
  volume = {8},
  number = {8},
  pages = {1418--1423},
  doi = {http://dx.doi.org/10.1166/jctn.2011.1830}
}
    C.Y. Xu, L.Z. Li, H. Li, R. Qin, J.X. Zheng, G.F. Luo, Q.H. Liu, X. Yan, L.L. Yu, J. Lu & Z.X. Gao Sign-changeable spin-filter efficiency and giant magnetoresistance in seamless graphene nanoribbon junctions

    [Abstract] [BibTeX]

    		 2011 Computational Materials Science
    Vol. 50(10), 2886-2890     		 DOI  
    Abstract: Sign-changeable spin-filter efficiency is predicted in both the ferromagnetic and antiferromagnetic configurations of a zigzag graphene nanoribbon bridging two half-planar graphene electrodes from ab initio quantum transport calculations. By changing edge spin-polarization configuration, we obtain giant room-temperature magnetoresistance, which is one order of magnitude larger than the maximum experimental results.
    Keywords: graphene nanoribbon; spin-filter efficiency; magnetoresistance; quantum transport calculation; room-temperature; transport; devices; graphite; gas; ATK; Application
    Area: graphene; spin
    BibTeX: 
    @article{Xu2011a,
  author = {Xu, C. Y. and Li, L. Z. and Li, H. and Qin, R. and Zheng, J. X. and Luo, G. F. and Liu, Q. H. and Yan, X. and Yu, L. L. and Lu, J. and Gao, Z. X.},
  title = {Sign-changeable spin-filter efficiency and giant magnetoresistance in seamless graphene nanoribbon junctions},
  journal = {Computational Materials Science},
  publisher = {Elsevier Science Bv},
  year = {2011},
  volume = {50},
  number = {10},
  pages = {2886--2890},
  doi = {http://dx.doi.org/10.1016/j.commatsci.2011.05.004}
}
    V.M.K. Bagci & C.C. Kaun Recognizing nucleotides by cross-tunneling currents for DNA sequencing

    [Abstract] [BibTeX]

    		 2011 Physical Review E
    Vol. 84(1), 011917     		 DOI  
    Abstract: Using first-principles calculations, we study electron transport through nucleotides inside a rectangular nanogap formed by two pairs of gold electrodes which are perpendicular and parallel to the nucleobase plane. We propose that this setup will enhance the nucleotide selectivity of tunneling signals to a great extent. Information from three electrical probing processes offers full nucleotide recognition, which survives the noise from neighboring nucleotides and configuration fluctuations.
    Keywords: transverse electronic transport; nanopore; molecule; nucleotides; DNA; bases; ATK; Application
    Area: molecular electronics
    BibTeX: 
    @article{Bagci2011,
  author = {Bagci, V. M. K. and Kaun, C. C.},
  title = {Recognizing nucleotides by cross-tunneling currents for DNA sequencing},
  journal = {Physical Review E},
  publisher = {Amer Physical Soc},
  year = {2011},
  volume = {84},
  number = {1},
  pages = {011917},
  doi = {http://dx.doi.org/10.1103/PhysRevE.84.011917}
}
    Kamal K. Saha, Marija Drndic & Branislav K. Nikolic DNA nucleotide-specific modulation of micro-ampere transverse edge currents through a metallic graphene nanoribbon with a nanopore

    [Abstract] [BibTeX]

    		 2011 Nano Letters
    Vol. Online firstarXiv:1108.3801v1 [cond-mat.mes-hall]     		 DOI URL 
    Abstract: We propose two-terminal devices for DNA sequencing which consist of a metallic graphene nanoribbon with zigzag edges (ZGNR) and a nanopore in its interior through which the DNA molecule is translocated. Using the nonequilibrium Green functions combined with density functional theory, we demonstrate that each of the four DNA nucleotides inserted into the nanopore, whose edge carbon atoms are passivated by either hydrogen or nitrogen, will lead to a unique change in the device conductance. Unlike other recent biosensors based on transverse electronic transport through DNA nucleotides, which utilize small (of the order of pA) tunneling current across a nanogap or a nanopore yielding a poor signal-to-noise ratio, our device concept relies on the fact that in ZGNRs local current density is peaked around the edges so that drilling a nanopore away from the edges will not diminish the conductance. Inserting a DNA nucleotide into the nanopore affects the charge density in the surrounding area, thereby modulating edge conduction currents whose magnitude is of the order of micro-A at bias voltage about 0.1 V. The proposed biosensor is not limited to ZGNRs and it could be realized with other nanowires supporting transverse edge currents, such as chiral GNRs or wires made of two-dimensional topological insulators.
    Keywords: ATK; Application; nanopore; DNA; graphene; biosensors;
    Area: graphene
    BibTeX: 
    @article{Saha2011,
  author = {Saha, Kamal K. and Drndic, Marija and Nikolic, Branislav K.},
  title = {DNA nucleotide-specific modulation of micro-ampere transverse edge currents through a metallic graphene nanoribbon with a nanopore},
  journal = {Nano Letters},
  year = {2011},
  volume = {Online first},
  url = {http://arxiv.org/abs/1108.3801},
  doi = {http://dx.doi.org/10.1021/nl202870y}
}
    Neeraj K. Jaiswal & Pankaj Srivastava First principles calculations of armchair graphene nanoribbons interacting with Cu atoms

    [Abstract] [BibTeX]

    		 2011 Physica E: Low-dimensional Systems and Nanostructures
    Vol. 44(1), 75-79     		 DOI  
    Abstract: We have investigated the electronic properties of bare, H-terminated, Cu-terminated and Cu-doped armchair graphene nanoribbons (AGNRs) using ab-initio approach. We found that H-termination enhances the stability and band gap whereas H extraction introduces dangling bands and lowers the band gap making bare ribbons indirect band gap semiconductors. The calculations revealed that strong hybridization between Cu atoms and AGNRs, lessen the band gap for Cu-terminated ribbons and gives rise to metallicity in Cu-doped AGNRs irrespective of their widths. Formation energy of considered ribbons yield that H-terminated AGNRs with lowest formation energy are most energetically favored, next are one edge Cu-terminated ribbons followed by bare ones whereas both edges Cu-doped ribbons are least energetically plausible. We predict that presence of Cu atoms in GNRs, significantly alter the band gap and can be used in band gap engineering of nanoribbons.
    Keywords: ATK; Application; graphene; doping;
    Area: graphene
    BibTeX: 
    @article{Jaiswal2011,
  author = {Neeraj K. Jaiswal and Pankaj Srivastava},
  title = {First principles calculations of armchair graphene nanoribbons interacting with Cu atoms},
  journal = {Physica E: Low-dimensional Systems and Nanostructures},
  year = {2011},
  volume = {44},
  number = {1},
  pages = {75-79},
  doi = {http://dx.doi.org/10.1016/j.physe.2011.07.009}
}
    Sudhanshu Choudhary & S. Qureshi Theoretical study on transport properties of a BN co-doped SiC nanotube

    [Abstract] [BibTeX]

    		 2011 Physics Letters A
    Vol. 375(38), 3382-3385     		 DOI  
    Abstract: We investigate the electronic transport properties of silicon carbide nanotubes (SiCNT) in presence of both boron (B) and nitrogen (N) impurities. The results show that co-doping BN impurities suppresses the important negative differential resistance (NDR) property. NDR suppression is attributed to the introduction of new electronic states near the Fermi level followed by weak orbital localization. BN co-doping results in exponential current-voltage (I-V ) characteristics which is in contrast to linear I-V characteristics for individual boron and nitrogen doped SiCNTs. HOMO has no contribution from B impurity, whereas, LUMO has contribution from N impurity at low and high bias.
    Keywords: Ab initio; SiC nanotube; impurities; co-doping; doping; negative differential resistance; NDR; ATK; Application
    Area: nanotubes
    BibTeX: 
    @article{Choudhary2011a,
  author = {Sudhanshu Choudhary and S. Qureshi},
  title = {Theoretical study on transport properties of a BN co-doped SiC nanotube},
  journal = {Physics Letters A},
  year = {2011},
  volume = {375},
  number = {38},
  pages = {3382-3385},
  doi = {http://dx.doi.org/10.1016/j.physleta.2011.08.001}
}
    D.D. Wu, F. Jiang, G. Yin, H. Chen, Y.Y. Liang, H. Mizuseki & Y. Kawazoe Hydrogenation-chain-opened conductive channels in zigzag graphene nanoribbons

    [Abstract] [BibTeX]

    		 2011 Journal of Applied Physics
    Vol. 110(3), 033712     		 DOI  
    Abstract: We discover a method of opening the conductive channels of zigzag graphene nanoribbons (ZGNRs) by using hydrogenation chains to separate the nanoribbon into two strips with a -0.7 Å distance, although the overall hydrogenation on graphene transforms the highly conductive semimetal sheet into an insulator. Two edge-like states emerge around each hydrogenation chain. The conductance enhancement, made by the hydrogenation chain, is found in nanoribbons with 5 to 7 chains, e.g. 5ZGNRH, 6ZGNRH, 7ZGNRH, and 7ZGNR2H (7ZGNR with two hydrogenation chains). The ZGNRs with hydrogenation chains illustrate their potential in nanoelectronics and carbon electronics as electronic leads and nonlinear devices.
    Keywords: graphene; hydrogenation; nanostructured materials; narrow band gap semiconductors; spin polarised transport; topological insulators; ATK; Application
    Area: graphene; spin
    BibTeX: 
    @article{Wu2011a,
  author = {D. D. Wu and F. Jiang and G. Yin and H. Chen and Y. Y. Liang and H. Mizuseki and Y. Kawazoe},
  title = {Hydrogenation-chain-opened conductive channels in zigzag graphene nanoribbons},
  journal = {Journal of Applied Physics},
  publisher = {AIP},
  year = {2011},
  volume = {110},
  number = {3},
  pages = {033712},
  doi = {http://dx.doi.org/10.1063/1.3614496}
}
    Z.Z. Lin & X.J. Ning Controlling the electronic properties of monatomic carbon chains

    [Abstract] [BibTeX]

    		 2011 Europhysics Letters
    Vol. 95(4), 47012     		 DOI  
    Abstract: Based on ab initio calculations, it is shown that the energy gap of pure monatomic carbon chains can be changed from 0.27 up to 1.42 eV when the chain is stretched by 10%, and the chains can be turned into n-type or p-type semiconductors by doping (B, N, Si, P) atoms or into rectification device by doping the BN molecule. The doping process was proved by Car-Parrinello molecular dynamics, and the lifetime of the doped chains is predicted to be about 10^70 years at room temperature. The results suggest that short monatomic carbon chains are a good candidate for tunable laser medium.
    Keywords: ATK; Application; atomic chain; quantum wire; doping; linear carbon; nanotube; electroluminescence; graphene; transport; junction; devices;
    Area: molecular electronics; nanowires
    BibTeX: 
    @article{Lin2011,
  author = {Z. Z. Lin and X. J. Ning},
  title = {Controlling the electronic properties of monatomic carbon chains},
  journal = {Europhysics Letters},
  year = {2011},
  volume = {95},
  number = {4},
  pages = {47012},
  doi = {http://dx.doi.org/10.1209/0295-5075/95/47012}
}
    Ali Hossain Khan, Qingmin Ji, Katsuhiko Ariga, Bidisa Das, D.D. Sarma & Somobrata Acharya Synthesis and metallic probe induced conductance of Au tipped ultranarrow PbS rods

    [Abstract] [BibTeX]

    		 2011 Chem. Commun.
    Vol. 47(29), 8421-8423     		 DOI  
    Abstract: Au tipped ultranarrow PbS nanorods are synthesized. DFT electronic structure calculations and transport studies show that Au probes modify the nature and energies of PbS nanorod orbitals creating efficient electron conduction channels for enhanced conductance even at low applied bias.
    Keywords: ATK; Application; nanorod; nanowire; conductance;
    Area: nanowires
    BibTeX: 
    @article{Khan2011,
  author = {Khan, Ali Hossain and Ji, Qingmin and Ariga, Katsuhiko and Das, Bidisa and Sarma, D. D. and Acharya, Somobrata},
  title = {Synthesis and metallic probe induced conductance of Au tipped ultranarrow PbS rods},
  journal = {Chem. Commun.},
  publisher = {The Royal Society of Chemistry},
  year = {2011},
  volume = {47},
  number = {29},
  pages = {8421--8423},
  doi = {http://dx.doi.org/10.1039/C1CC12339D}
}
    Yuqing Xu, Changfeng Fang, Bin Cui, Guomin Ji, Yaxin Zhai & Desheng Liu Gated electronic currents modulation and designs of logic gates with single molecular field effect transistors

    [Abstract] [BibTeX]

    		 2011 Applied Physics Letters
    Vol. 99(4), 043304     		 DOI  
    Abstract: The electronic transport properties of a gated single 1,3-benzenedithiol molecular device are studied by using nonequilibrium Green's function in combination with density functional theory, which is hoped to complement the experiments. The results show that the external transverse gate electrodes can effectively tune the electronic transport properties of the molecular devices. Negative differential resistance behaviors are observed almost at the same source-drain bias when applied different gate voltages. Mechanisms are proposed for these phenomena. Designs of using one gated molecular device to realize five basic logic gates are also put forward.
    Keywords: density functional theory; Green's function methods; logic gates; molecular electronics; organic compounds; organic field effect transistors; quantum transport; switch; ATK; Application
    Area: molecular electronics
    BibTeX: 
    @article{Xu2011,
  author = {Yuqing Xu and Changfeng Fang and Bin Cui and Guomin Ji and Yaxin Zhai and Desheng Liu},
  title = {Gated electronic currents modulation and designs of logic gates with single molecular field effect transistors},
  journal = {Applied Physics Letters},
  publisher = {AIP},
  year = {2011},
  volume = {99},
  number = {4},
  pages = {043304},
  doi = {http://dx.doi.org/10.1063/1.3615691}
}
    Yi-Peng An, Zhongqin Yang & Mark A. Ratner High-efficiency switching effect in porphyrin-ethyne-benzene conjugates

    [Abstract] [BibTeX]

    		 2011 Journal of Chemical Physics
    Vol. 135(4), 044706     		 DOI  
    Abstract: We have explored the electronic transport properties of porphyrin-ethyne-benzene conjugates using an ab initio method. The results indicate that these ethyne-bridged phenyl porphyrin molecules can be used as candidates for molecular switching devices. The coplanar conformation of phenyl and porphyrin moieties allows a far larger current than the perpendicular conformation due to the near vanishing overlap of the frontier molecular orbitals (pi channels) in the porphyrin and phenyl parts in the latter. Higher current ratios of ON/OFF states can be obtained if amino or nitro substituent is placed at the position meta to the bridge connecting the pi systems of the molecule. The substituent group affects the electronic state energy of the entire molecule in coplanar conformation, while only affecting the local part in perpendicular conformation. More complex ethyne-bridged diphenyl porphyrin molecules are found to yield more complex and interesting switching effects. Our results suggest that such molecular wires composed of appropriate pi-conjugated molecules, can generally display perfect switching function and the efficiency can be tuned flexibly by adding certain substituent groups to the conjugates.
    Keywords: ab initio calculations; electrical conductivity transitions; molecular electronics; organic compounds; single-molecule junction; electron-transfer; controlled conductance; transport; transistor; dependence; resistance; geometry; wires; ATK; Application
    Area: molecular electronics
    BibTeX: 
    @article{An2011,
  author = {Yi-Peng An and Zhongqin Yang and Mark A. Ratner},
  title = {High-efficiency switching effect in porphyrin-ethyne-benzene conjugates},
  journal = {Journal of Chemical Physics},
  publisher = {AIP},
  year = {2011},
  volume = {135},
  number = {4},
  pages = {044706},
  doi = {http://dx.doi.org/10.1063/1.3615492}
}
    L.H. Wang, Y. Guo & B.J. Ding Effect of the encapsulation of Li atom on the electronic transport properties of C20F20 cage

    [Abstract] [BibTeX]

    		 2011 Physica B: Condensed Matter
    Vol. 406(18), 3442 - 3445     		 DOI URL 
    Abstract: Carrying out theoretical calculations using a self-consistent ab initio approach that combines the non-equilibrium Green's function formalism with density functional theory, we investigate the effect of the center encapsulation of Li atom on the electronic transport properties of C20F20 cage sandwiched between two bulk gold electrodes. The results show that the electrical conductivity of the endohedral complex Li@C20F20 becomes better than that of the empty C20F20 in the bias voltages ranging from 0 to 1.2 V. The novel negative differential resistance behavior in the I-V characteristic curves can be observed by inserting Li atom into C20F20 cage. The mechanism for the negative differential resistance behavior of Li@C20F20 is suggested.
    Keywords: density functional theory; non-equilibrium green's function; electronic transport property; negative differential resistance; single-molecule conductance; complexes; junctions; rectification; transistor; surfaces; exchange; contact; thiol; cage molecule; ATK; Application
    Area: molecular electronics; fullerenes
    BibTeX: 
    @article{Wang2011b,
  author = {L.H. Wang and Y. Guo and B.J. Ding},
  title = {Effect of the encapsulation of Li atom on the electronic transport properties of C20F20 cage},
  journal = {Physica B: Condensed Matter},
  year = {2011},
  volume = {406},
  number = {18},
  pages = {3442 - 3445},
  url = {http://www.sciencedirect.com/science/article/pii/S0921452611005655},
  doi = {http://dx.doi.org/10.1016/j.physb.2011.06.016}
}
    P. Zhao, D.S. Liu, Y. Zhang, Y. Su, S.J. Li & G. Chen Negative differential resistance in the unsymmetrical C121-based molecular junction

    [Abstract] [BibTeX]

    		 2011 Physics Letters A
    Vol. 375(27), 2639-2643     		 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 the unsymmetrical C121-based molecular junction. Our results show that the current-voltage curve displays a negative differential resistance phenomenon in a certain bias voltage range. The mechanism for the negative differential resistance phenomenon is suggested. The present findings could be helpful for the application of the C121 molecule in the field of single molecular devices or nanometer electronics.
    Keywords: Fullerenes; Non-equilibrium Green's function; Electronic transport; Negative differential resistance; ATK; Application
    Area: fullerenes
    BibTeX: 
    @article{Zhao2011c,
  author = {Zhao, P. and Liu, D.S. and Zhang, Y. and Su, Y. and Li, S.J. and Chen, G.},
  title = {Negative differential resistance in the unsymmetrical C121-based molecular junction},
  journal = {Physics Letters A},
  year = {2011},
  volume = {375},
  number = {27},
  pages = {2639--2643},
  url = {http://www.sciencedirect.com/science/article/pii/S0375960111006426},
  doi = {http://dx.doi.org/10.1016/j.physleta.2011.05.044}
}
    Vihar P. Georgiev & John E. McGrady Influence of Low-Symmetry Distortions on Electron Transport through Metal Atom Chains: When Is a Molecular Wire Really "Broken"?

    [Abstract] [BibTeX]

    		 2011 Journal of the American Chemical Society
    Vol. 133(32), 12590-12599     		 DOI  
    Abstract: In the field of molecular electronics, an intimate link between the delocalization of molecular orbitals and their ability to support current flow is often assumed. Delocalization, in turn, is generally regarded as being synonymous with structural symmetry, for example, in the lengths of the bonds along a molecular wire. In this work, we use density functional theory in combination with nonequilibrium Green's functions to show that precisely the opposite is true in the extended metal atom chain Cr3(dpa)4(NCS)2 where the delocalized pi framework has previously been proposed to be the dominant conduction pathway. Low-symmetry distortions of the Cr3 core do indeed reduce the effectiveness of these pi channels, but this is largely irrelevant to electron transport at low bias simply because they lie far below the Fermi level. Instead, the dominant pathway is through higher-lying orbitals of sigma symmetry, which remain essentially unperturbed by even quite substantial distortions. In fact, the conductance is actually increased marginally because the sigma-nb channel is displaced upward toward the Fermi level. These calculations indicate a subtle and counterintuitive relationship between structure and function in these metal chains that has important implications for the interpretation of data emerging from scanning tunnelling and atomic force microscopy experiments.
    Keywords: ATK; Application; molecular electronics; delocalization; molecular orbitals; metal atom chain; conductance
    Area: molecular electronics
    BibTeX: 
    @article{Georgiev2011,
  author = {Georgiev, Vihar P. and McGrady, John E.},
  title = {Influence of Low-Symmetry Distortions on Electron Transport through Metal Atom Chains: When Is a Molecular Wire Really "Broken"?},
  journal = {Journal of the American Chemical Society},
  publisher = {American Chemical Society},
  year = {2011},
  volume = {133},
  number = {32},
  pages = {12590-12599},
  doi = {http://dx.doi.org/10.1021/ja2028475}
}
    Hua Hao, XiaoHong Zheng, ZhenXiang Dai & Zhi Zeng Gate-induced switching in single-molecule magnet Mn(III)Cu(II)

    [Abstract] [BibTeX]

    		 2011 Journal of Applied Physics
    Vol. 110(2), 023702     		 DOI  
    Abstract: Gate voltage effect on electronic transport through the smallest single-molecule magnet (SMM) MnCu [MnIIICuIICl(5-Br-sap)2(MeOH)] sandwiched between Au(100) electrodes is investigated by spin-polarized density functional theory calculations combined with the Keldysh nonequilibrium Green's technique. Our study demonstrates that a certain gate voltage can induce a switching of the conductance in the equilibrium state. Under a finite bias voltage, negative differential resistance is observed in this system and can be modulated by tuning the gate voltage. More interestingly, current rectification can be achieved at a certain negative gate voltage. These effects can be understood by the responses of the benzene rings and the magnetic core to an external electrical field.
    Keywords: transport; magnetization; spin; molecular electronics; density functional theory; electrical resistivity; gold; Green's function methods; magnetic materials; molecular magnetism; organic compounds; rectification; spin polarised transport; switching; ATK; Application
    Area: molecular electronics; spin
    BibTeX: 
    @article{Hao2011,
  author = {Hua Hao and XiaoHong Zheng and ZhenXiang Dai and Zhi Zeng},
  title = {Gate-induced switching in single-molecule magnet Mn(III)Cu(II)},
  journal = {Journal of Applied Physics},
  publisher = {AIP},
  year = {2011},
  volume = {110},
  number = {2},
  pages = {023702},
  doi = {http://dx.doi.org/10.1063/1.3610448}
}
    Kai-Tak Lam, Marie Stephen Leo, Chengkuo Lee & Gengchiau Liang Design evaluation of graphene nanoribbon nanoelectromechanical devices

    [Abstract] [BibTeX]

    		 2011 Journal of Applied Physics
    Vol. 110(2), 024302     		 DOI  
    Abstract: Computational studies on nanoelectromechanical switches based on bilayer graphene nanoribbons (BGNRs) with different designs are presented in this work. By varying the interlayer distance via electrostatic means, the conductance of the BGNR can be changed in order to achieve ON-states and OFF-states, thereby mimicking the function of a switch. Two actuator designs based on the modified capacitive parallel plate (CPP) model and the electrostatic repulsive force (ERF) model are discussed for different applications. Although the CPP design provides a simple electrostatic approach to changing the interlayer distance of the BGNR, their switching gate bias VTH strongly depends on the gate area, which poses a limitation on the size of the device. In addition, there exists a risk of device failure due to static fraction between the mobile and fixed electrodes. In contrast, the ERF design can circumvent both issues with a more complex structure. Finally, optimizations of the devices are carried out in order to provide insights into the design considerations of these nanoelectromechanical switches.
    Keywords: actuators; fullerene devices; graphene; nanoelectromechanical devices; nanostructured materials; switches; ATK; Application
    Area: graphene
    BibTeX: 
    @article{Lam2011a,
  author = {Kai-Tak Lam and Marie Stephen Leo and Chengkuo Lee and Gengchiau Liang},
  title = {Design evaluation of graphene nanoribbon nanoelectromechanical devices},
  journal = {Journal of Applied Physics},
  publisher = {AIP},
  year = {2011},
  volume = {110},
  number = {2},
  pages = {024302},
  doi = {http://dx.doi.org/10.1063/1.3606578}
}
    Jing Zeng, Ke-Qiu Chen, Jun He, Zhi-Qiang Fan & Xiao-Jiao Zhang Nitrogen doping-induced rectifying behavior with large rectifying ratio in graphene nanoribbons device

    [Abstract] [BibTeX]

    		 2011 Journal of Applied Physics
    Vol. 109(12), 124502     		 DOI  
    Abstract: By applying nonequilibrium Green's functions in combination with density-function theory, we investigate the electronic transport properties of armchair graphene nanoribbons devices with one undoped and one nitrogen-doped armchair graphene nanoribbons electrode. For the doped armchair graphene nanoribbons electrode, an N dopant is considered to substitute the center or edge carbon atom. The results show that the electronic transport properties are strongly dependent on the width of the ribbon and the position of the N dopant. The rectifying behavior with large rectifying ratio can be observed and can be modulated by changing the width of the ribbon or the position of the N dopant. A mechanism for the rectifying behavior is suggested.
    Keywords: density functional theory; graphene; Green's function methods; nanostructured materials; nitrogen; rectification; semiconductor doping; ATK; Application
    Area: graphene
    BibTeX: 
    @article{Zeng2011d,
  author = {Jing Zeng and Ke-Qiu Chen and Jun He and Zhi-Qiang Fan and Xiao-Jiao Zhang},
  title = {Nitrogen doping-induced rectifying behavior with large rectifying ratio in graphene nanoribbons device},
  journal = {Journal of Applied Physics},
  publisher = {AIP},
  year = {2011},
  volume = {109},
  number = {12},
  pages = {124502},
  doi = {http://dx.doi.org/10.1063/1.3600067}
}
    A. Zienert, J. Schuster, R. Streiter & T. Gessner Quantum mechanical methods for the simulation of electronic transport through carbon nanotubes

    [Abstract] [BibTeX]

    		 2011 Interconnect Technology Conference and 2011 Materials for Advanced Metallization (IITC/MAM), 2011 IEEE International, 1 -3  DOI  
    Abstract: In the present work we study electronic transport properties of finite length single-wall carbon nanotubes. A simple model is used to describe the electrodes and the way they are attached to both ends of the CNT. Electronic transport calculations are carried out on three different levels of sophistication. Those are single orbital tight-binding, extended Hückel and density functional theory in combination with Green's function methods. Results are compared and discussed.
    Keywords: ATK; ATK-SE; Application; nanotube;
    Area: nanotubes
    BibTeX: 
    @inproceedings{Zienert2011,
  author = {Zienert, A. and Schuster, J. and Streiter, R. and Gessner, T.},
  title = {Quantum mechanical methods for the simulation of electronic transport through carbon nanotubes},
  booktitle = {Interconnect Technology Conference and 2011 Materials for Advanced Metallization (IITC/MAM), 2011 IEEE International},
  year = {2011},
  pages = {1 -3},
  doi = {http://dx.doi.org/10.1109/IITC.2011.5940363}
}
    William D. Wheeler, B.A. Parkinson & Yuri Dahnovsky The adsorption energy and diffusion of a pentacene molecule on a gold surface

    [Abstract] [BibTeX]

    		 2011 Journal of Chemical Physics
    Vol. 135(2), 024702     		 DOI  
    Abstract: The nature of the chemical bonding of a pentacene molecule to a gold surface is studied. The calculations are carried out using two very different methodologies, the ab inito gaussian molecular orbital method and a numerical atomic orbital method, developed from the well tested SIESTA approach. Using the GAUSSIAN 09 package, we employ both local density B3LYP, and long-range correlated functionals CAM-B3LYP, omega-B97, and omega-B97X. For comparison, we also calculate the adsorption energy using the ATOMISTIX TOOLKIT with the revised PBE functional. Within computational and experimental errors we find that the best description of the binding energies can be obtained from GAUSSIAN calculations using long-range omega-B97 and omega-B97X exchange functionals. Thus the nature of chemical bonding of a pentacene to gold is a van der Waals type. To understand the large variation in the geometries computed by different methods, we calculate energy profiles in both X- and Y-directions. The energy barriers appear to be very small and comparable with the value of room temperature. Thus a pentacene molecule moves on a gold surface with almost no friction at room temperatures. An estimation of the work function is often obtained from a simple electrostatic approach. We test this estimation and find that this approach cannot be used because it significantly underestimates the work function. This investigation gives insights into the structure and bonding of pentacene to a gold surface and provides ideas for the improvement of methodologies for computing the properties of van der Waals adsorbates.
    Keywords: ab initio calculations; adsorption; binding energy; bonds (chemical); density functional theory; diffusion; geometry; GO calculations; gold; organic compounds; molecular electronics; ATK; Application
    Area: molecular electronics
    BibTeX: 
    @article{Wheeler2011,
  author = {William D. Wheeler and B. A. Parkinson and Yuri Dahnovsky},
  title = {The adsorption energy and diffusion of a pentacene molecule on a gold surface},
  journal = {Journal of Chemical Physics},
  publisher = {AIP},
  year = {2011},
  volume = {135},
  number = {2},
  pages = {024702},
  doi = {http://dx.doi.org/10.1063/1.3599088}
}
    D.H. Zhang, K.L. Yao & G.Y. Gao The peculiar transport properties in p-n junctions of doped graphene nanoribbons

    [Abstract] [BibTeX]

    		 2011 Journal of Applied Physics
    Vol. 110(1), 013718     		 DOI  
    Abstract: Two kinds of junctions based on doped graphene nanoribbons (GNRs) are designed and studied in this article. One is the N-doped armchair GNR (AGNR) joined directly by B-doped AGNRs, and another is similar, but there is an undoped AGNR between them. The transport properties are calculated using the full self-consistent ab initio nonequilibrium Green's function and density-functional theory methods under external bias. We find that the I-V curves for both junctions have a striking nonlinear feature and show large negative differential resistance properties, not only at the positive bias but also at the negative one. The results also indicate that the diode-like properties are kept and the rectification coefficient is very high within a wide bias region. Our calculations reveal that the formation of these peculiar transport behaviors is due to the great changes of the transmission spectra and the projected self-consistent Hamiltonian eigenvalues with the applied bias voltage. These findings suggest that the doped AGNRs may offer unique opportunities for the future development of nanoscale electronics.
    Keywords: ab initio calculations; boron; density functional theory; eigenvalues and eigenfunctions; elemental semiconductors; graphene; Green's function methods; nanostructured materials; negative resistance; nitrogen; p-n heterojunctions; rectification; SCF calculations; ATK; Application
    Area: graphene
    BibTeX: 
    @article{Zhang2011c,
  author = {D. H. Zhang and K. L. Yao and G. Y. Gao},
  title = {The peculiar transport properties in p-n junctions of doped graphene nanoribbons},
  journal = {Journal of Applied Physics},
  publisher = {AIP},
  year = {2011},
  volume = {110},
  number = {1},
  pages = {013718},
  doi = {http://dx.doi.org/10.1063/1.3605489}
}
    K Shiiki Simulation of tunneling magneto-resistance in Fe/MgO/Fe junction

    [Abstract] [BibTeX]

    		 2011 Journal of Physics: Conference Series
    Vol. 303(1), 012101     		 DOI URL 
    Abstract: The conductivity asymmetry of junctions with insulating MgO barriers embedded between ferromagnetic Fe electrodes has been investigated by the first principles calculation program of Atomistix ToolKit 2008. The conductivity in up-spin electron is larger than that in down-spin electron for the ideal structure. It leads to the large TMR ratio. The defect of O or Fe atoms hardly varies the conductivity in both up and down-spin electrons. The defect of Mg atoms increases the conductivity in down-spin electron, although the up-spin conductivity does not change very much. So the defect of Mg decreases the TMR ratio. The defect of Mg near the interface especially shows this degradation. The derivative conductivity dI / dV vs. V characteristics are asymmetric for the polarity of the bias voltage V according to the location of the atom defect. The quality of the junction in devices can be evaluated by the asymmetry.
    Keywords: ATK; Application; spin; magneto-resistance; MTJ; defects; strain
    Area: interfaces; spin
    BibTeX: 
    @article{Shiiki2011,
  author = {K Shiiki},
  title = {Simulation of tunneling magneto-resistance in Fe/MgO/Fe junction},
  journal = {Journal of Physics: Conference Series},
  year = {2011},
  volume = {303},
  number = {1},
  pages = {012101},
  url = {http://stacks.iop.org/1742-6596/303/i=1/a=012101},
  doi = {http://dx.doi.org/10.1088/1742-6596/303/1/012101}
}
    Manabu Kiguchi, Takuya Takahashi, Yuta Takahashi, Yoshihiro Yamauchi, Takashi Murase, Makoto Fujita, Tomofumi Tada & Satoshi Watanabe Electron Transport through Single Molecules Comprising Aromatic Stacks Enclosed in Self-Assembled Cages

    [BibTeX]

    		 2011 Angewandte Chemie International Edition
    Vol. 50(25), 5708-5711     		 DOI  
    Keywords: electron transfer, molecular electronics, nanogap electrode, pi interactions, single-molecule studies, ATK, Application
    Area: molecular electronics
    BibTeX: 
    @article{Kiguchi2011a,
  author = {Kiguchi, Manabu and Takahashi, Takuya and Takahashi, Yuta and Yamauchi, Yoshihiro and Murase, Takashi and Fujita, Makoto and Tada, Tomofumi and Watanabe, Satoshi},
  title = {Electron Transport through Single Molecules Comprising Aromatic Stacks Enclosed in Self-Assembled Cages},
  journal = {Angewandte Chemie International Edition},
  publisher = {WILEY-VCH Verlag},
  year = {2011},
  volume = {50},
  number = {25},
  pages = {5708--5711},
  doi = {http://dx.doi.org/10.1002/anie.201100431}
}
    Xiao-Fei Li, Ling-Ling Wang, Ke-Qiu Chen & Yi Luo Design of Graphene-Nanoribbon Heterojunctions from First Principles

    [Abstract] [BibTeX]

    		 2011 The Journal of Physical Chemistry C
    Vol. 115(25), 12616-12624     		 DOI  
    Abstract: Graphene nanoribbons with armchair and zigzag edges are known to have very different electronic structure and properties. We show here that the fusion of an armchair and a zigzag graphene-nanoribbon (aGNR|zGNR) can form heterojunctions with remarkable electron transport properties. First-principles calculations reveal that the heterojunction can be either metallic or semiconducting depending on the width of the nanoribbon. A well-defined oscillation of the zero-bias conductance as a function of the ribbon width is observed, which is originated from the resonance and nonresonance of frontier orbitals between aGNR and zGNR. We find that the current/voltage characteristics of the aGNR|zGNR heterojunction possess pronounced rectification effect, and a high rectification ratio can be achieved by tuning the width of the zGNR to minimize the backward current. The unique properties of the proposed heterojunction could be very useful for manufacturing graphene-based electronic devices.
    Keywords: ATK; Application; graphene nanoribbon heterojunction; rectification
    Area: graphene
    BibTeX: 
    @article{Li2011d,
  author = {Li, Xiao-Fei and Wang, Ling-Ling and Chen, Ke-Qiu and Luo, Yi},
  title = {Design of Graphene-Nanoribbon Heterojunctions from First Principles},
  journal = {The Journal of Physical Chemistry C},
  year = {2011},
  volume = {115},
  number = {25},
  pages = {12616-12624},
  doi = {http://dx.doi.org/10.1021/jp202188t}
}
    Qihang Liu, Guangfu Luo, Rui Qin, Hong Li, Xin Yan, Chengyong Xu, Lin Lai, Jing Zhou, Shimin Hou, Enge Wang, Zhengxiang Gao & Jing Lu Negative differential resistance in parallel single-walled carbon nanotube contacts

    [Abstract] [BibTeX]

    		 2011 Phys. Rev. B
    Vol. 83(15), 155442-     		 DOI  
    Abstract: Based on first-principles calculations, we investigate the electron transport properties of parallel single-walled carbon nanotube contact. A significant negative differential resistance (NDR) behavior is found due to staggered electron gratings in energy space and standing waves in real space on the two tubes induced by bias. Such a NDR effect is robust against the contact length, the tube diameter, the shape of the end, and the difference in the two electrodes. Because no bridging molecule is used, the structure of this NDR device is simpler compared with ordinary molecular NDR devices. Our findings are expected to promote the discovery of more NDR devices composed of only two electrodes in parallel contact.
    Keywords: ATK; Application; nanotube; negative differential resistance; NDR
    Area: nanotubes
    BibTeX: 
    @article{Liu2011d,
  author = {Liu, Qihang and Luo, Guangfu and Qin, Rui and Li, Hong and Yan, Xin and Xu, Chengyong and Lai, Lin and Zhou, Jing and Hou, Shimin and Wang, Enge and Gao, Zhengxiang and Lu, Jing},
  title = {Negative differential resistance in parallel single-walled carbon nanotube contacts},
  journal = {Phys. Rev. B},
  publisher = {American Physical Society},
  year = {2011},
  volume = {83},
  number = {15},
  pages = {155442--},
  doi = {http://dx.doi.org/10.1103/PhysRevB.83.155442}
}
    Pei Zhao, Ji-Ming Zheng, You-Wei Chen, Ping Guo & Zhao-Yu Ren Theoretical investigation on electron transport properties of single wall carbon nanotube with oxygen molecular absorption

    [Abstract] [BibTeX]

    		 2011 Acta Physica Sinica
    Vol. 60(6), 068501     		 URL 
    Abstract: Electron transport properties of (4,4) single wall carbon nanotube as well as the nanotube with oxygen molecule absorption, are investigated by using first principles analysis. The results show that electron current through the nanotube with oxygen molecule absorption system increases linearly under low bias ranging from 0 to 1.1 V, while the bias is larger than 1.1 V, the current through this system increases slowly. It is also shown that absorbed oxygen molecule brings two kinds of influence on the properties of electron transport: first, the oxygen molecular absorbed states afford new channels to electron transport and enhance the transmission. Second, the oxygen molecular absorbed states spoil the nanotube's symmetry and enhance the electron scattering, so reduce the transmission.
    Keywords: ATK; Application; single wall carbon nanotube; oxygen molecular absorption; electron transport; non-equilibrium Green's functions
    Area: nanotubes
    BibTeX: 
    @article{Zhao2011a,
  author = {Zhao, Pei and Zheng, Ji-Ming and Chen, You-Wei and Guo, Ping and Ren, Zhao-Yu},
  title = {Theoretical investigation on electron transport properties of single wall carbon nanotube with oxygen molecular absorption},
  journal = {Acta Physica Sinica},
  year = {2011},
  volume = {60},
  number = {6},
  pages = {068501},
  url = {http://wulixb.iphy.ac.cn/cn/ch/common/view_abstract.aspx?file_no=w201106119&flag=1}
}
    S. Choudhary & S. Qureshi Effect of radial and axial deformation on electron transport properties in a semiconducting Si-C nanotube

    [Abstract] [BibTeX]

    		 2011 Journal of Nano- and Electronic Physics
    Vol. 3(1), 584-589     		 URL 
    Abstract: We study the bias voltage dependent current characteristic 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 transmission spectra and electron density of states at zero bias shows a significant reduction in threshold in the case of both radially compressed and axially elongated nanotube. However, semiconductor to metal transition was not observed, though the results show large differences in current characteristic compared to a perfect nanotube.
    Keywords: ATK; Application; nanotubes; SiC; defects; deformation;
    Area: nanotubes
    BibTeX: 
    @article{Choudhary2011,
  author = {S. Choudhary and S. Qureshi},
  title = {Effect of radial and axial deformation on electron transport properties in a semiconducting Si-C nanotube},
  journal = {Journal of Nano- and Electronic Physics},
  year = {2011},
  volume = {3},
  number = {1},
  pages = {584-589},
  url = {http://jnep.sumdu.edu.ua/index.php?option=com_content&task=full_article&id=212&lang=en}
}
    YaXin Zhai, GuoMin Ji, ChangFeng Fang, Bin Cui, Peng Zhao & DeSheng Liu Negative differential resistance in molecular devices: the role of molecule-electrode coupling

    [Abstract] [BibTeX]

    		 2011 SCIENCE CHINA Physics, Mechanics & Astronomy
    Vol. 54(8), 1455-1460     		 DOI  
    Abstract: By applying nonequilibrium Green's function formalism combined with the first-principles density functional theory, we investigate the electronic transport in two molecular junctions constituted by a substituted oligo (phenylene ehtynylene) sandwiched between two Au electrodes. Our calculations show that the weak molecule-electrode coupling is responsible for the observation of the negative differential resistance (NDR) effect in experiments. When the coupling is weak, the projected density of states (PDOS) of the molecule and the electrodes undergoes a mismatch-match-mismatch procedure, which increases and then decreases the transmission peak intensities, leading to a NDR effect. We also find that the localization/delocalization of the molecular orbitals and the change of charge state of the molecule have no direct relation with the NDR effect, because they change little as the voltage increases.
    Keywords: ATK; Application; molecular electronics; negative differential resistance; NDR; substituted oligo (phenylene ehtynylene); molecular junction; density functional theory; nonequilibrium Green's function formalism
    Area: molecular electronics
    BibTeX: 
    @article{Zhai2011,
  author = {Zhai, YaXin and Ji, GuoMin and Fang, ChangFeng and Cui, Bin and Zhao, Peng and Liu, DeSheng},
  title = {Negative differential resistance in molecular devices: the role of molecule-electrode coupling},
  journal = {SCIENCE CHINA Physics, Mechanics & Astronomy},
  publisher = {Science China Press, co-published with Springer},
  year = {2011},
  volume = {54},
  number = {8},
  pages = {1455-1460},
  doi = {http://dx.doi.org/10.1007/s11433-011-4406-x}
}
    Zhi-Qiang Fan & Ke-Qiu Chen Controllable rectifying performance in a C60 molecular device with asymmetric electrodes

    [Abstract] [BibTeX]

    		 2011 Journal of Applied Physics
    Vol. 109(12), 124505     		 DOI URL 
    Abstract: By using nonequilibrium Green's functions in combination with the density-functional theory, we investigate the current-voltage character of a single C60 molecule sandwiched between Au electrode and carbon nanotube electrode theoretically. The calculated results show that the asymmetric electrodes connecting is of significant influence on the transport properties. By adjusting the matching of orbitals around the Fermi level among the two electrodes and the molecule, the rectifying behavior of the device can be realized and the rectification ratio can be modulated.
    Keywords: carbon nanotubes; density functional theory; electrodes; Fermi level; fullerene devices; fullerenes; gold; Green's function methods; metal-insulator boundaries; rectification; ATK; Application
    Area: nanotubes; fullerenes
    BibTeX: 
    @article{Fan2011,
  author = {Zhi-Qiang Fan and Ke-Qiu Chen},
  title = {Controllable rectifying performance in a C60 molecular device with asymmetric electrodes},
  journal = {Journal of Applied Physics},
  publisher = {AIP},
  year = {2011},
  volume = {109},
  number = {12},
  pages = {124505},
  url = {http://link.aip.org/link/?JAP/109/124505/1},
  doi = {http://dx.doi.org/10.1063/1.3597789}
}
    Xinqian Li, Aleksandar Staykov & Kazunari Yoshizawa Orbital views of the electron transport through heterocyclic aromatic hydrocarbons

    [Abstract] [BibTeX]

    		 2011 Theoretical Chemistry Accounts: Theory, Computation, and Modeling (Theoretica Chimica Acta)
    Vol. 130, 765-774     		 DOI  
    Abstract: Electron-transport properties of heterocyclic aromatic hydrocarbons are investigated with theoretical methods. The present study is based on a previously derived concept for orbital control of electron transport through aromatic hydrocarbons. The orbital control concept provided crucial basic understanding for the best conductance channels in the aromatic hydrocarbons and was successfully applied in the design of molecular devices. That concept was proven to hold true for small aromatic molecules, large polycyclic aromatic hydrocarbons with different edge structures, and in weak and strong coupling with the electrodes junctions. The polycyclic aromatic hydrocarbons and nanographenes used in the molecular electronics are often immobilized with different types of defects, which require the application of the orbital control concept on heterocyclic aromatic hydrocarbons. In this work, the effect of the heteroatoms in aromatic hydrocarbons on their electron-transport properties and the applicability of the orbital control concept on heterocyclic aromatic hydrocarbons are studied. Effective routes for electron transport are predicted in weak coupling junctions by analyzing the phase and amplitude of the frontier orbitals. The qualitative predictions are made with the nonequilibrium Green's function method combined with the Hückel approximation. Quantitative, first principle calculations are performed with the nonequilibrium Green's function method combined with density functional theory. The obtained results are in good agreement with the expectations on the basis of the orbital control concept, which proves its applicability in heterocyclic aromatic hydrocarbons.
    Keywords: ATK; Application; molecular electronics; nonequilibrium Green's function; orbital symmetry rule; electron-transport properties; heterocyclic aromatic hydrocarbons
    Area: molecular electronics
    BibTeX: 
    @article{Li2011c,
  author = {Li, Xinqian and Staykov, Aleksandar and Yoshizawa, Kazunari},
  title = {Orbital views of the electron transport through heterocyclic aromatic hydrocarbons},
  journal = {Theoretical Chemistry Accounts: Theory, Computation, and Modeling (Theoretica Chimica Acta)},
  publisher = {Springer Berlin / Heidelberg},
  year = {2011},
  volume = {130},
  pages = {765-774},
  doi = {http://dx.doi.org/10.1007/s00214-011-0968-y}
}
    JiaSai Ma, DongMei Li, YaXin Zhai & Peng Zhao Negative differential resistance in a molecular junction of carbon nanotube and benzene

    [Abstract] [BibTeX]

    		 2011 SCIENCE CHINA Physics, Mechanics & Astronomy
    Vol. 54(8), 1433-1437     		 DOI  
    Abstract: We propose a novel molecular junction with single-walled carbon nanotubes as electrodes bridged by a benzene molecule, in which the electrodes are saturated by different terminations (C-, H- and N-). It is found that the different terminations at the carbon nanotube ends strongly affect the electronic transport properties of the junction. The current-voltage (I-V) curve of the N-terminated carbon nanotube junction shows a more striking nonlinear feature than that of the C- and H-terminated junctions at small bias. Moreover, the negative differential resistance behaviors can be observed significantly in the N-terminated carbon nanotube junction, whereas not in the other two cases.
    Keywords: ATK; Application; negative differential resistance; carbon nanotube; electronic transport; non-equilibrium Green's function
    Area: nanotubes
    BibTeX: 
    @article{Ma2011,
  author = {Ma, JiaSai and Li, DongMei and Zhai, YaXin and Zhao, Peng},
  title = {Negative differential resistance in a molecular junction of carbon nanotube and benzene},
  journal = {SCIENCE CHINA Physics, Mechanics & Astronomy},
  publisher = {Science China Press, co-published with Springer},
  year = {2011},
  volume = {54},
  number = {8},
  pages = {1433-1437},
  doi = {http://dx.doi.org/10.1007/s11433-011-4392-z}
}
    Zhizhou Yu, M.L. Hu, C.X. Zhang, C.Y. He, L.Z. Sun & Jianxin Zhong Transport Properties of Hybrid Zigzag Graphene and Boron Nitride Nanoribbons

    [Abstract] [BibTeX]

    		 2011 The Journal of Physical Chemistry C
    Vol. 115(21), 10836-10841     		 DOI URL 
    Abstract: The transport properties of hybrid nanoribbons formed by partially substituting zigzag boron nitride (graphene) nanoribbons into zigzag graphene (boron nitride) nanoribbons are investigated using the first-principles nonequilibrium Green's function method. The transport properties are highly improved with the transmission conductance around the Fermi level increasing to 3G0 in hybrid systems based on zigzag graphene nanoribbons and to 2G0 in hybrid systems based on zigzag boron nitride nanoribbons. The enhancement is 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 transport enhancement also remains in hybrid nanoribbons sandwiched into gold electrodes. The currents of such devices are improved compared with those of pristine ones, which originate from the additional transport channels at the C-B interface.
    Keywords: ATK; Application; graphene; boron-nitride nanoribbon; transport properties; NEGF;
    Area: graphene
    BibTeX: 
    @article{Yu2011a,
  author = {Yu, Zhizhou and Hu, M. L. and Zhang, C. X. and He, C. Y. and Sun, L. Z. and Zhong, Jianxin},
  title = {Transport Properties of Hybrid Zigzag Graphene and Boron Nitride Nanoribbons},
  journal = {The Journal of Physical Chemistry C},
  year = {2011},
  volume = {115},
  number = {21},
  pages = {10836-10841},
  url = {http://pubs.acs.org/doi/abs/10.1021/jp200870t},
  doi = {http://dx.doi.org/10.1021/jp200870t}
}
    Salvador Rodríguez-Bolívar, Francisco M. Gómez-Campos, Luis Álvarez de Cienfuegos, Noelia Fuentes, Diego J. Cárdenas, Elena Buñuel, Juan E. Carceller, Andrés Parra & Juan M. Cuerva Conductance and application of organic molecule pairs as nanofuses

    [Abstract] [BibTeX]

    		 2011 Phys. Rev. B
    Vol. 83(12), 125424     		 DOI  
    Abstract: We propose that a pair of organic molecules can mimic the behavior of a macroscopic fuse at nanoscale, one component of the pair being the on state and the other the off state. For this task we make use of density-functional theory to calculate the physical properties of selected molecules, which have also been synthesized by our team. By this means we obtain the transmission spectra and the current of the proposed devices, which allows us to compare the behavior of the on and off states. Of particular interest is the on/off switch ratios, defined as the current ratios of the on and off structures at the corresponding bias voltage. In a first stage, we examine the best linker between the device and the electrode for high on/off switch ratios. Once this is determined, we test the influence of the electron richness of the system to provide a high on/off switch ratio. The entire analysis is also supported by the molecular projected self-consistent Hamiltonian, which provides a good way of understanding the molecular behavior. All the calculations support that interesting on/off switch ratios of two orders of magnitude could be obtained with these prototypical nanofuses.
    Keywords: ATK; Application; molecular electronics; nanoscale fuse; nanofuse; experimental comparison;
    Area: molecular electronics
    BibTeX: 
    @article{PhysRevB.83.125424,
  author = {Rodríguez-Bolívar, Salvador and Gómez-Campos, Francisco M. and Álvarez de Cienfuegos, Luis and Fuentes, Noelia and Cárdenas, Diego J. and Buñuel, Elena and Carceller, Juan E. and Parra, Andrés and Cuerva, Juan M.},
  title = {Conductance and application of organic molecule pairs as nanofuses},
  journal = {Phys. Rev. B},
  publisher = {American Physical Society},
  year = {2011},
  volume = {83},
  number = {12},
  pages = {125424},
  doi = {http://dx.doi.org/10.1103/PhysRevB.83.125424}
}
    Satyendra Singh Chauhan, Pankaj Srivastava & Rajnish Kurchania Half-Metallicity in Doped Armchair Graphene Nanoribbons - An Ab Initio Approach

    [Abstract] [BibTeX]

    		 2011 Journal of Computational and Theoretical Nanoscience
    Vol. 8, 729-735     		 DOI URL 
    Abstract: We present a comprehensive theoretical study based on density functional theory for stability, electronic and transport properties of armchair graphene nanoribbons. We have tested boron, beryllium, lithium, magnesium, fluorine, oxygen and nitrogen as substitutional dopant in the center of armchair graphene nanoribbons. It is observed that oxygen atom as substitutional dopant in armchair graphene nanoribbons is energetically more favorable and it also minimizes the band gap in all tested widths of armchair graphene nanoribbons (AGNRs). Moreover the oxygen doping at the center of ribbon predicts the half-metallicty in AGNRs. The transport properties are found to be influenced by edge doping of oxygen in AGNRs. These substitutional oxygen atoms act as scattering centers for the electronic transport along the nanoribbons. Since transmission is sensitive to O doping, so our results point towards the relative suitability of O doped armchair edge for sensor applications.
    Keywords: ATK; Application; half-metallicity; doping; graphene nanoribbons
    Area: graphene; spin
    BibTeX: 
    @article{Chauhan2011,
  author = {Chauhan, Satyendra Singh and Srivastava, Pankaj and Kurchania, Rajnish},
  title = {Half-Metallicity in Doped Armchair Graphene Nanoribbons - An Ab Initio Approach},
  journal = {Journal of Computational and Theoretical Nanoscience},
  year = {2011},
  volume = {8},
  pages = {729-735},
  url = {http://www.ingentaconnect.com/content/asp/jctn/2011/00000008/00000004/art00029},
  doi = {http://dx.doi.org/10.1166/jctn.2011.1745}
}
    Hongguang Cheng, Zuli Liu & Kailun Yao Rectifying behavior in La[sub 2/3]Sr[sub 1/3]MnO[sub 3]/MgO/SrRuO[sub 3] magnetic tunnel junctions

    [Abstract] [BibTeX]

    		 2011 Applied Physics Letters
    Vol. 98(17), 172107     		 DOI URL 
    Abstract: We report first principles calculations of transport properties of the all-oxide La2/3Sr1/3MnO3/MgO/SrRuO3 magnetic tunnel junctions. A sizeable rectifying behavior which can be enhanced by increasing the MgO barrier thickness is predicted theoretically. For the device with 13 layers of MgO barrier, the positive current is about two orders of magnitude larger than the reverse leakage current. The rectifying behavior arises from the symmetry-filtering properties of the MgO barrier. This rectifying effect which is totally dominated by quantum tunneling could be used to design faster quantum devices such as tunnel diode and tunnel transistor.
    Keywords: ab initio calculations; interface magnetism; lanthanum compounds; leakage currents; magnesium compounds; magnetic tunnelling junction; rectification; strontium compounds; ATK; Application; MTJ;
    Area: interfaces; spin
    BibTeX: 
    @article{Cheng2011a,
  author = {Hongguang Cheng and Zuli Liu and Kailun Yao},
  title = {Rectifying behavior in La[sub 2/3]Sr[sub 1/3]MnO[sub 3]/MgO/SrRuO[sub 3] magnetic tunnel junctions},
  journal = {Applied Physics Letters},
  publisher = {AIP},
  year = {2011},
  volume = {98},
  number = {17},
  pages = {172107},
  url = {http://link.aip.org/link/?APL/98/172107/1},
  doi = {http://dx.doi.org/10.1063/1.3586242}
}
    Morad M. El-Hendawy, Ahmed M. El-Nahas & Mohamed K. Awad The effect of constitutional and conformational isomerization on the electrical properties of diblock molecular diode

    [Abstract] [BibTeX]

    		 2011 Organic Electronics
    Vol. 12(6), 1080 - 1092     		 DOI URL 
    Abstract: The ultimate goal of this paper is to introduce new links between the chemical response of the molecule to the electric field and the physics of cell involving the molecule. Density functional theory (DFT) calculations were preformed to investigate the effect of constitutional and conformational isomerization on the electrical properties of the dipyrimidinyl-diphenyl dithiol (DPDPh1) as a diblock molecular diode. The non-equilibrium Green's function approach combined with DFT (NEGF-DFT) has been used to compute the current-voltage characteristics in order to support the obtained results. The calculations could differentiate among the isomers regarding their rectification efficiency. Moreover, plots of the global electrophilicity index and the tendency of constitutional isomers to receive charge from the circuit against applied voltage show I-V curve feature. The conformational analysis has been done through examining the effect of structural twist on the current, dipole moment, HOMO energy, and molecular gain of the DPDPh1 molecule. The rectification is slightly affected by twisting because of the limited change in molecular polarization. However, the results demonstrated that the insertion of a CH2-spacer or twisting the donor and acceptor parts of the DPDPh1 molecule by 90° generates an Aviram-Ratner-like diode where the HOMO and LUMO are localized on the donor and acceptor subunits, respectively.
    Keywords: molecular diode; ATK; Application; electrophilicity; rectification
    Area: molecular electronics
    BibTeX: 
    @article{El-Hendawy2011,
  author = {Morad M. El-Hendawy and Ahmed M. El-Nahas and Mohamed K. Awad},
  title = {The effect of constitutional and conformational isomerization on the electrical properties of diblock molecular diode},
  journal = {Organic Electronics},
  year = {2011},
  volume = {12},
  number = {6},
  pages = {1080 - 1092},
  url = {http://www.sciencedirect.com/science/article/pii/S1566119911001017},
  doi = {http://dx.doi.org/10.1016/j.orgel.2011.03.022}
}
    Fang-Ping OuYang, Sheng-Lin Peng, Hua Zhang, Li-Bo Weng & Hui Xu A biosensor based on graphene nanoribbon with nanopores: a first-principles devices-design

    [Abstract] [BibTeX]

    		 2011 Chinese Physics B
    Vol. 20(5), 058504     		 DOI  
    Abstract: A biosensor device, built from graphene nanoribbons (GNRs) with nanopores, was designed and studied by first-principles quantum transport simulation. We have demonstrated the intrinsic transport properties of the device and the effect of different nucleobases on device properties when they are located in the nanopores of GNRs. It was found that the device's current changes remarkably with the species of nucleobases, which originates from their different chemical compositions and coupling strengths with GNRs. In addition, our first-principles results clearly reveal that the distinguished ability of a device's current depends on the position of the pore to some extent. These results may present a new way to read off the nucleobases sequence of a single-stranded DNA (ssDNA) molecule by such GNRs-based device with designed nanopores
    Keywords: ATK; Application; DNA; biosensors; graphene nanoribbon; defects;
    Area: graphene
    BibTeX: 
    @article{Fang-Ping2011,
  author = {OuYang, Fang-Ping and Peng, Sheng-Lin and Zhang, Hua and Weng, Li-Bo and Xu, Hui},
  title = {A biosensor based on graphene nanoribbon with nanopores: a first-principles devices-design},
  journal = {Chinese Physics B},
  year = {2011},
  volume = {20},
  number = {5},
  pages = {058504},
  doi = {http://dx.doi.org/10.1088/1674-1056/20/5/058504}
}
    Song Jiuxu, Yang Yintang, Liu Hongxia & Guo Lixin Negative differential resistance in an (8,0) carbon/boron nitride nanotube heterojunction

    [Abstract] [BibTeX]

    		 2011 Journal of Semiconductors
    Vol. 32(4), 042003     		 DOI URL 
    Abstract: Using the method combined non-equilibrium Green's function with density functional theory, the electronic transport properties of an (8, 0) carbon/boron nitride nanotube heterojunction coupled to Au electrodes were investigated. In the current voltage characteristic of the heterojunction, negative differential resistance was found under positive and negative bias, which is the variation of the localization for corresponding molecular orbital caused by the applied bias voltage. These results are meaningful to modeling and simulating on related electronic devices.
    Keywords: ATK; Application; nanotubes; NDR; negative differential resistance
    Area: nanotubes
    BibTeX: 
    @article{Jiuxu2011,
  author = {Song Jiuxu and Yang Yintang and Liu Hongxia and Guo Lixin},
  title = {Negative differential resistance in an (8,0) carbon/boron nitride nanotube heterojunction},
  journal = {Journal of Semiconductors},
  year = {2011},
  volume = {32},
  number = {4},
  pages = {042003},
  url = {http://stacks.iop.org/1674-4926/32/i=4/a=042003},
  doi = {http://dx.doi.org/10.1088/1674-4926/32/4/042003}
}
    Manabu Kiguchi, Takuya Takahashi, Yuta Takahashi, Yoshihiro Yamauchi, Takashi Murase, Makoto Fujita, Tomofumi Tada & Satoshi Watanabe Electron Transport through Single Molecules Comprising Aromatic Stacks Enclosed in Self-Assembled Cages

    [Abstract] [BibTeX]

    		 2011 Angewandte Chemie
    Vol. 123(25), 5826-5829     		 DOI  
    Abstract: Der Elektronentransport entlang eines pi-Stapels zwischen Nanolücken-Goldelektroden wurde mit STM gemessen. Selbstorganisierte Koordinationskäfige, die pi-gestapelte aromatische Moleküle enthalten, sind leitfähig, der leere Käfig dagegen nicht.

    [Electron transport along a pi-chain between nano gap gold electrodes were measured with STM. Self-organized coordination cages, which contain the pi-stacked molecules, are conducting, while the empty cages are not.]
    Keywords: single molecular studies; electron transfer; molecular electronics; nanogap electrode; ATK; Application
    Area: molecular electronics
    BibTeX: 
    @article{Kiguchi2011,
  author = {Kiguchi, Manabu and Takahashi, Takuya and Takahashi, Yuta and Yamauchi, Yoshihiro and Murase, Takashi and Fujita, Makoto and Tada, Tomofumi and Watanabe, Satoshi},
  title = {Electron Transport through Single Molecules Comprising Aromatic Stacks Enclosed in Self-Assembled Cages},
  journal = {Angewandte Chemie},
  publisher = {WILEY-VCH Verlag},
  year = {2011},
  volume = {123},
  number = {25},
  pages = {5826--5829},
  doi = {http://dx.doi.org/10.1002/ange.201100431}
}
    Yanwei Li, Jinhuan Yao, Shengkui Zhong & Zhengguang Zou Theoretical investigations on the orientational dependence of electron transport through porphyrin molecular wire

    [Abstract] [BibTeX]

    		 2011 Current Applied Physics
    Vol. 11, 1349-1353     		 DOI  
    Abstract: The effect of molecular orientation on the electron transport behavior of single porphyrin sandwiched between two gold (111) electrodes is investigated by density functional theory calculations combined with non-equilibrium Green's function method. The results show that the porphyrin with parallel connection to gold (111) electrodes is more conductive than the porphyrin with diagonal connection to gold (111) electrodes. The mechanism of the difference of electron transport for these two molecular junctions is analyzed from the transmission spectra and the molecular projected self-consistent Hamiltonian states. It is found that the intrinsic nature of the molecule, such as the p-conjugated framework and the strength of moleculeeelectrode coupling, are the essential reason for generating this difference of electron transport for the two molecular systems.
    Keywords: electron transport; porphyrin; non-equilibrium Green's function; molecular electronics; ATK; Application
    Area: molecular electronics
    BibTeX: 
    @article{Li2011b,
  author = {Yanwei Li and Jinhuan Yao and Shengkui Zhong and Zhengguang Zou},
  title = {Theoretical investigations on the orientational dependence of electron transport through porphyrin molecular wire},
  journal = {Current Applied Physics},
  year = {2011},
  volume = {11},
  pages = {1349-1353},
  doi = {http://dx.doi.org/10.1016/j.cap.2011.04.001}
}
    An Liping & Liu Nianhua First-principles study on transport properties of zigzag graphene nanoribbon with different spin-configurations

    [Abstract] [BibTeX]

    		 2011 Journal of Semiconductors
    Vol. 32(5), 052001     		 DOI  
    Abstract: The current-voltage (I-V) characteristics and the transmission spectra of zigzag graphene nanoribbon with different spin-configurations are investigated by using first-principles calculations. It is shown that the I-V curves and transmission spectra strongly depend on the spin-configurations of the two sides of the ribbon. For the spin-parallel configuration structure, the curve is linear under lower bias voltage; for the spin-antiparallel configuration structure, there is a strong spin-polarization-dependent transmission which implies that the ribbon can be used as a spin filter; while for other spin-configuration structures, the curve has the characteristics of a semiconductor. It is found that there is a large magneto-resistance (MR) when the bias voltage is small. The impurity in the central scattering region significantly influences the spin-dependent current and the spin filter efficiency, which may lead the large MR to disappear.
    Keywords: ATK; Application; graphene; magneto-resistance; spin filter;
    Area: graphene; spin
    BibTeX: 
    @article{Liping2011,
  author = {An Liping and Liu Nianhua},
  title = {First-principles study on transport properties of zigzag graphene nanoribbon with different spin-configurations},
  journal = {Journal of Semiconductors},
  year = {2011},
  volume = {32},
  number = {5},
  pages = {052001},
  doi = {http://dx.doi.org/10.1088/1674-4926/32/5/052001}
}
    Guo-Ying Tu, Da-Peng Guo, Bing-Rui Li & Hao-Li Zhang Transport properties and mechanism of C60 coupled to carbon nanotube electrode

    [Abstract] [BibTeX]

    		 2011 Physica B: Condensed Matter
    Vol. 406(11), 2138 - 2142     		 DOI URL 
    Abstract: By applying non-equilibrium Green's functions in combination with density-functional theory, we investigate electronic transport properties of C60 coupled to carbon nanotubes and Li electrodes. The results show that electronic transport properties of CNT-C60-CNT and Li-C60-Li systems are completely different. Nonlinear I-V characteristic, varistor-type behavior and negative differential resistance (NDR) phenomenon are observed when electrodes are carbon nanotubes. We discuss the mechanism of I-V characteristics of CNT-C60-CNT systems in details. Our results suggest conductance, energy level of Frontier molecular orbitals, energy gap between HOMO and LUMO, the coupling between molecular orbitals and electrodes are all playing critical roles in electronic transport properties.
    Keywords: Transport properties; ATK; Application; fullerene; C60; carbon nanotubes; negative differential resistance; NDR; CNT
    Area: nanotubes; fullerenes
    BibTeX: 
    @article{Tu2011,
  author = {Guo-Ying Tu and Da-Peng Guo and Bing-Rui Li and Hao-Li Zhang},
  title = {Transport properties and mechanism of C60 coupled to carbon nanotube electrode},
  journal = {Physica B: Condensed Matter},
  year = {2011},
  volume = {406},
  number = {11},
  pages = {2138 - 2142},
  url = {http://www.sciencedirect.com/science/article/pii/S0921452611002250},
  doi = {http://dx.doi.org/10.1016/j.physb.2011.03.016}
}
    Cai Juan Xia, Ying Tang Zhang & Xue Jun Zai Effects of Different Metal-Molecule Interface Conformations on the Electronic Transport in Molecular Junctions

    [Abstract] [BibTeX]

    		 2011 Materials Science Forum
    Vol. 663-665, 588-591     		 DOI  
    Abstract: Based on nonequilibrium Green's function and first-principles calculation, we investigate the electronic transport of borazine molecule with different metal-molecule interface conformations, namely bridge and top site. The motivation is the variable situations that may arise in break junction experiments. Numerical results show that the current will be increased with the different adsorption sites; especially the enhancement of current is more obvious when molecule is located at the bridge site. Furthermore, a negative differential resistance under applied bias can be observed when the molecule is located at the top site. The mechanism of negative differential resistance is mainly induced by the resonance peak around the Fermi energy in top adsorption site.
    Keywords: Density Functional Theory (DFT), Electronic Transport, Interface Conformation, Negative Differential Resistance, Nonequilibrium Green's Function, ATK, Application
    Area: molecular electronics
    BibTeX: 
    @article{Xia2011a,
  author = {Xia, Cai Juan and Zhang, Ying Tang and Zai, Xue Jun},
  title = {Effects of Different Metal-Molecule Interface Conformations on the Electronic Transport in Molecular Junctions},
  journal = {Materials Science Forum},
  year = {2011},
  volume = {663-665},
  pages = {588-591},
  doi = {http://dx.doi.org/10.4028/www.scientific.net/MSF.663-665.588}
}
    Cai Juan Xia, Han Chen Liu & Ying Tang Zhang The Quantum Length Dependence of Conductance in Molecular Device: An Ab Initio Study

    [Abstract] [BibTeX]

    		 2011 Materials Science Forum
    Vol. 663-665, 519-522     		 DOI  
    Abstract: By applying nonequilibrium Green's function formalism combined first-principles density functional theory, we investigate the electronic transport properties of thiophene and furan molecules with different quantum length. 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 results show that the transport behaviors are determined by the distinct electronic structures of the molecular compounds. the length dependence of molecular conductance exhibits its diversity for different molecules.
    Keywords: Density Functional Theory (DFT), Electronic Transport, Nonequilibrium Green's Function, Quantum Length, ATK, Application
    Area: molecular electronics
    BibTeX: 
    @article{Xia2011f,
  author = {Xia, Cai Juan and Liu, Han Chen and Zhang, Ying Tang},
  title = {The Quantum Length Dependence of Conductance in Molecular Device: An Ab Initio Study},
  journal = {Materials Science Forum},
  year = {2011},
  volume = {663-665},
  pages = {519-522},
  doi = {http://dx.doi.org/10.4028/www.scientific.net/MSF.663-665.519}
}
    Cai-Juan Xia, De-Sheng Liu, Han-Chen Liu & Xue-Jun Zhai Large negative differential resistance in a molecular device with asymmetric contact geometries: A first-principles study

    [Abstract] [BibTeX]

    		 2011 Physica E: Low-dimensional Systems and Nanostructures
    Vol. 43(8), 1518 - 1521     		 DOI URL 
    Abstract: We report a first-principles study of electronic transport properties and negative differential resistance (NDR) in a single molecular device consisting of a pyrene-based molecule sandwiched between two gold electrodes with different contact geometries. The results show that the electronic transport properties are strongly dependent on the contact geometry. 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 NDR.
    Keywords: ATK; Application; molecular electronics; negative differential resistance; NDR; contact geometry;
    Area: molecular electronics
    BibTeX: 
    @article{Xia2011g,
  author = {Cai-Juan Xia and De-Sheng Liu and Han-Chen Liu and Xue-Jun Zhai},
  title = {Large negative differential resistance in a molecular device with asymmetric contact geometries: A first-principles study},
  journal = {Physica E: Low-dimensional Systems and Nanostructures},
  year = {2011},
  volume = {43},
  number = {8},
  pages = {1518 - 1521},
  url = {http://www.sciencedirect.com/science/article/pii/S1386947711001330},
  doi = {http://dx.doi.org/10.1016/j.physe.2011.04.020}
}
    G P Zhang, X W Fang, Y X Yao, C Z Wang, Z J Ding & K M Ho Electronic structure and transport of a carbon chain between graphene nanoribbon leads

    [Abstract] [BibTeX]

    		 2011 Journal of Physics: Condensed Matter
    Vol. 23(2), 025302     		 DOI URL 
    Abstract: The electronic structure and transport property of a carbon chain between two graphene nanoribbon leads are studied using an ab initio tight-binding (TB) model and Landauer's formalism combined with a non-equilibrium Green's function. The TB Hamiltonian and overlap matrices are extracted from first-principles density functional calculations through the quasi-atomic minimal basis orbital scheme. The accuracy of the TB model is demonstrated by comparing the electronic structure from the TB model with that from first-principles density functional theory. The results of electronic transport on a carbon atomic chain connected to armchair and zigzag graphene ribbon leads, such as different transport characters near the Fermi level and at most one quantized conductance, reveal the effect of the electronic structure of the leads and the scattering from the atomic chain. In addition, bond length alternation and an interesting transmission resonance are observed in the atomic chain connected to zigzag graphene ribbon leads. Our approach provides a promising route to quantitative investigation of both the electronic structure and transport property of large systems.
    Keywords: ATK; Application; graphene; carbon chain;
    Area: graphene
    BibTeX: 
    @article{Zhang2011b,
  author = {G P Zhang and X W Fang and Y X Yao and C Z Wang and Z J Ding and K M Ho},
  title = {Electronic structure and transport of a carbon chain between graphene nanoribbon leads},
  journal = {Journal of Physics: Condensed Matter},
  year = {2011},
  volume = {23},
  number = {2},
  pages = {025302},
  url = {http://stacks.iop.org/0953-8984/23/i=2/a=025302},
  doi = {http://dx.doi.org/10.1088/0953-8984/23/2/025302}
}
    Anurag Srivastava, Neha Tyagi & R.K. Singh Structural and electronic properties of lead nanowires: Ab-initio study

    [Abstract] [BibTeX]

    		 2011 Materials Chemistry and Physics
    Vol. 127(3), 489 - 494     		 DOI URL 
    Abstract: Ab-initio self-consistent study has been performed to analyze the stability of lead nanowires in its six stable configurations like linear, zigzag, triangular, ladder, square and dumbbell. In the present study, the lowest energy structures have been analyzed under the revised Perdew-Burke-Ernzerhof (revPBE) parameterization of generalized gradient approximation (GGA) potential. The two-atom zigzag shaped atomic configuration with highest binding energy and lowest total energy has been confirmed as the most stable structure out of the six atomic configurations. The electronic band structure and density of states have been discussed in detail with a remarkable observation in case of three-atom triangular lead nanowire having a very small band gap while other configurations are found to be metallic. Bulk modulus, pressure derivatives and lattice parameters for different lead nanowires have also been computed and discussed.
    Keywords: Metals, nanostructures, ab initio calculations, computer modeling and simulation, computational techniques, band-structure, ATK, Application, nanowires
    Area: nanowires
    BibTeX: 
    @article{Srivastava2011,
  author = {Anurag Srivastava and Neha Tyagi and R.K. Singh},
  title = {Structural and electronic properties of lead nanowires: Ab-initio study},
  journal = {Materials Chemistry and Physics},
  year = {2011},
  volume = {127},
  number = {3},
  pages = {489 - 494},
  url = {http://www.sciencedirect.com/science/article/pii/S0254058411001556},
  doi = {http://dx.doi.org/10.1016/j.matchemphys.2011.02.044}
}
    Yuta Tsuji, Aleksandar Staykov & Kazunari Yoshizawa Orbital Views of Molecular Conductance Perturbed by Anchor Units

    [Abstract] [BibTeX]

    		 2011 Journal of the American Chemical Society
    Vol. 133(15), 5955-5965     		 DOI URL 
    Abstract: Site-specific electron transport phenomena through benzene and benzenedithiol derivatives are discussed on the basis of a qualitative Hückel molecular orbital analysis for better understanding of the effect of anchoring sulfur atoms. A recent work for the orbital control of electron transport through aromatic hydrocarbons provided an important concept for the design of high-conductance connections of a molecule with anchoring atoms. In this work the origin of the frontier orbitals of benzenedithiol derivatives, the effect of the sulfur atoms on the orbitals and on the electron transport properties, and the applicability of the theoretical concept on aromatic hydrocarbons with the anchoring units are studied. The results demonstrate that the orbital view predictions are applicable to molecules perturbed by the anchoring units. The electron transport properties of benzene are found to be qualitatively consistent with those of benzenedithiol with respect to the site dependence. To verify the result of the Hückel molecular orbital calculations, fragment molecular orbital analyses with the extended Hückel molecular orbital theory and electron transport calculations with density functional theory are performed. Calculated results are in good agreement with the orbital interaction analysis. The phase, amplitude, and spatial distribution of the frontier orbitals play an essential role in the design of the electron transport properties through aromatic hydrocarbons.
    Keywords: ATK; Application; molecular electronics;
    Area: molecular electronics
    BibTeX: 
    @article{Tsuji2011,
  author = {Tsuji, Yuta and Staykov, Aleksandar and Yoshizawa, Kazunari},
  title = {Orbital Views of Molecular Conductance Perturbed by Anchor Units},
  journal = {Journal of the American Chemical Society},
  year = {2011},
  volume = {133},
  number = {15},
  pages = {5955-5965},
  url = {http://pubs.acs.org/doi/abs/10.1021/ja111021e},
  doi = {http://dx.doi.org/10.1021/ja111021e}
}
    Z L Zhang, Y P Chen, Y E Xie, M Zhang & J X Zhong Spin-polarized transport properties of Fe atomic chain adsorbed on zigzag graphene nanoribbons

    [Abstract] [BibTeX]

    		 2011 Journal of Physics D: Applied Physics
    Vol. 44(21), 215403     		 DOI URL 
    Abstract: The spin-polarized transport properties of Fe atomic chain adsorbed on zigzag graphene nanoribbons (ZGNRs) are investigated using the density-functional theory in combination with the nonequilibrium Green's function method. We find that the Fe chain has drastic effects on spin-polarized transport properties of ZGNRs compared with a single Fe atom adsorbed on the ZGNRs. When the Fe chain is adsorbed on the centre of the ZGNR, the original semiconductor transforms into metal, showing a very wide range of spin-polarized transport. Particularly, the spin polarization around the Fermi level is up to 100%. This is because the adsorbed Fe chain not only induces many localized states but also has effects on the edge states of ZGNR, which can effectively modulate the spin-polarized transports. The spin polarization of ZGNRs is sensitive to the adsorption site of the Fe chain. When the Fe chain is adsorbed on the edge of ZGNR, the spin degeneracy of conductance is completely broken. The spin polarization is found to be more pronounced because the edge state of one edge is destroyed by the additional Fe chain. These results have direct implications for the control of the spin-dependent conductance in ZGNRs with the adsorption of Fe chains.
    Keywords: ATK; Application; graphene; spin polarization;
    Area: graphene; spin
    BibTeX: 
    @article{Zhang2011a,
  author = {Z L Zhang and Y P Chen and Y E Xie and M Zhang and J X Zhong},
  title = {Spin-polarized transport properties of Fe atomic chain adsorbed on zigzag graphene nanoribbons},
  journal = {Journal of Physics D: Applied Physics},
  year = {2011},
  volume = {44},
  number = {21},
  pages = {215403},
  url = {http://stacks.iop.org/0022-3727/44/i=21/a=215403},
  doi = {http://dx.doi.org/10.1088/0022-3727/44/21/215403}
}
    Y.D. Guo, X.H. Yan & Y. Xiao Multiple negative differential resistance and the modulation in a nanotubelike fullerene D[sub 5h](1)-C[sub 90]

    [Abstract] [BibTeX]

    		 2011 Applied Physics Letters
    Vol. 98(16), 163107     		 DOI URL 
    Abstract: We have preformed a first-principle calculation on the electronic transport properties of a recently synthesized nanotubelike fullerene D5h(1)-C90. One finds three negative differential resistance regions in the I-V curve, which could be modulated by gate voltage and contact configuration. Further analysis showed that, the charge transfer and molecule-electrode coupling, induced by both bias and gate voltages, are responsible for the observed phenomena.
    Keywords: ab initio calculations; charge transfer states; density functional theory; electrical contacts; electronic structure; fullerenes; negative resistance; ATK; Application
    Area: fullerenes
    BibTeX: 
    @article{Guo2011,
  author = {Y. D. Guo and X. H. Yan and Y. Xiao},
  title = {Multiple negative differential resistance and the modulation in a nanotubelike fullerene D[sub 5h](1)-C[sub 90]},
  journal = {Applied Physics Letters},
  publisher = {AIP},
  year = {2011},
  volume = {98},
  number = {16},
  pages = {163107},
  url = {http://link.aip.org/link/?APL/98/163107/1},
  doi = {http://dx.doi.org/10.1063/1.3582238}
}
    M.L. Hu, Zhizhou Yu, K.W. Zhang, L.Z. Sun & J.X. Zhong Tunneling Magnetoresistance of Bilayer Hexagonal Boron Nitride and Its Linear Response to External Uniaxial Strain

    [Abstract] [BibTeX]

    		 2011 The Journal of Physical Chemistry C
    Vol. 115(16), 8260-8264     		 DOI  
    Abstract: Using density functional theory and nonequilibrium Green's function method, we investigate the tunneling magnetoresistance (TMR) of the magnetotunnel junctions (MTJs) based on bilayer hexagonal boron nitride and its response to external uniaxial strain. The TMR ratio increases linearly with the increasing uniaxial strain because the increasing uniaxial strain reduces the bandgap of bilayer hexagonal boron nitride gradually. Interestingly, the TMR ratio exceeds 95% when the uniaxial strain increases to 2.51%, which is close to that of the perfect spin filter. Our results indicate that the bilayer hexagonal boron nitride is a promising candidate for the spacer of MTJs. Moreover, its TMR ratio can be linearly modulated by external uniaxial strain.
    Keywords: ATK; Application; boron nitride; tunneling magnetoresistance; TMR; strain; magnetic tunnel junction; MTJ;
    Area: interfaces; spin
    BibTeX: 
    @article{Hu2011,
  author = {Hu, M. L. and Yu, Zhizhou and Zhang, K. W. and Sun, L. Z. and Zhong, J. X.},
  title = {Tunneling Magnetoresistance of Bilayer Hexagonal Boron Nitride and Its Linear Response to External Uniaxial Strain},
  journal = {The Journal of Physical Chemistry C},
  publisher = {American Chemical Society},
  year = {2011},
  volume = {115},
  number = {16},
  pages = {8260--8264},
  doi = {http://dx.doi.org/10.1021/jp109971r}
}
    Yutaka Ie, Tomoya Hirose, Hisao Nakamura, Manabu Kiguchi, Noriaki Takagi, Maki Kawai & Yoshio Aso Nature of Electron Transport by Pyridine-Based Tripodal Anchors: Potential for Robust and Conductive Single-Molecule Junctions with Gold Electrodes

    [Abstract] [BibTeX]

    		 2011 Journal of the American Chemical Society
    Vol. 133(9), 3014-3022     		 DOI URL 
    Abstract: We have designed and synthesized a pyridine-based tripodal anchor unit to construct a single-molecule junction with a gold electrode. The advantage of tripodal anchoring to a gold surface was unambiguously demonstrated by cyclic voltammetry measurements. X-ray photoelectron spectroscopy measurements indicated that the pi orbital of pyridine contributes to the physical adsorption of the tripodal anchor unit to the gold surface. The conductance of a single-molecule junction that consists of the tripodal anchor and diphenyl acetylene was measured by modified scanning tunneling microscope techniques and successfully determined to be 5 ± 1 × 10^-4 G0. Finally, by analyzing the transport mechanism based on ab initio calculations, the participation of the pi orbital of the anchor moieties was predicted. The tripodal structure is expected to form a robust junction, and pyridine is predicted to achieve pi-channel electric transport.
    Keywords: ATK; Application; molecular electronics;
    Area: molecular electronics
    BibTeX: 
    @article{Ie2011,
  author = {Ie, Yutaka and Hirose, Tomoya and Nakamura, Hisao and Kiguchi, Manabu and Takagi, Noriaki and Kawai, Maki and Aso, Yoshio},
  title = {Nature of Electron Transport by Pyridine-Based Tripodal Anchors: Potential for Robust and Conductive Single-Molecule Junctions with Gold Electrodes},
  journal = {Journal of the American Chemical Society},
  year = {2011},
  volume = {133},
  number = {9},
  pages = {3014-3022},
  url = {http://pubs.acs.org/doi/abs/10.1021/ja109577f},
  doi = {http://dx.doi.org/10.1021/ja109577f}
}
    Sang Uck Lee, Rodion V. Belosludov, Hiroshi Mizuseki & Yoshiyuki Kawazoe Electron transport characteristics of organic molecule encapsulated carbon nanotubes

    [Abstract] [BibTeX]

    		 2011 Nanoscale
    Vol. 3(4), 1773-1779     		 DOI  
    Abstract: One-dimensional carbon nanotube (CNT) junctions with interesting device characteristics have been designed by encapsulating p- and n-type organic molecules into CNTs with electrophilic tetracyano-p-quinodimethane (TCNQ) and nucleophilic tetrakis(dimethylamino)ethylene (TDAE) molecules in order to explore the effect of encapsulation of organic molecules and rectifying behaviors of the designed one-dimensional CNT p-n junctions. Our results show that p- and n-type doping of CNTs and their associated charge transfer play an important role in determining the electron transport characteristics and lead to materials with unique properties, p-n junction diode, i.e. Zener-like diode. Furthermore, we show that the operational device characteristics of non-covalently doped CNT junctions originate from the distinct response of intrinsic transmission peaks of pure CNTs according to the type of dopant and the applied bias. We believe that the results give an insight into the design and implementation of various electronic logic functions based on CNTs for applications in the field of nanoelectronics.
    Keywords: ATK; Application; carbon nanotubes; rectification; p-n junction; charge transfer; Zener diode; doping; nanoelectronics
    Area: nanotubes
    BibTeX: 
    @article{Lee2011,
  author = {Lee, Sang Uck and Belosludov, Rodion V. and Mizuseki, Hiroshi and Kawazoe, Yoshiyuki},
  title = {Electron transport characteristics of organic molecule encapsulated carbon nanotubes},
  journal = {Nanoscale},
  publisher = {The Royal Society of Chemistry},
  year = {2011},
  volume = {3},
  number = {4},
  pages = {1773--1779},
  doi = {http://dx.doi.org/10.1039/C0NR00757A}
}
    Linze Li, Rui Qin, Hong Li, Lili Yu, Qihang Liu, Guangfu Luo, Zhengxiang Gao & Jing Lu Functionalized Graphene for High-Performance Two-Dimensional Spintronics Devices

    [Abstract] [BibTeX]

    		 2011 ACS Nano
    Vol. 5(4), 2601-2610     		 DOI URL 
    Abstract: Using first-principles calculations, we explore the possibility of functionalized graphene as a high-performance two-dimensional spintronics device. Graphene functionalized with O on one side and H on the other side in the chair conformation is found to be a ferromagnetic metal with a spin-filter efficiency up to 54% at finite bias. The ground state of graphene semifunctionalized with F in the chair conformation is an antiferromagnetic semiconductor, and we construct a spin-valve device from it by introducing a magnetic field to stabilize its metallic ferromagnetic state. The resulting room-temperature magnetoresistance is up to 2200%, which is 1 order of magnitude larger than the available experimental values.
    Keywords: functionalized graphene; spintronics; spin-filter efficiency; magnetoresistance; first-principles calculations; graphone; graphene; ATK; Application
    Area: graphene; spin
    BibTeX: 
    @article{Li2011a,
  author = {Li, Linze and Qin, Rui and Li, Hong and Yu, Lili and Liu, Qihang and Luo, Guangfu and Gao, Zhengxiang and Lu, Jing},
  title = {Functionalized Graphene for High-Performance Two-Dimensional Spintronics Devices},
  journal = {ACS Nano},
  year = {2011},
  volume = {5},
  number = {4},
  pages = {2601-2610},
  url = {http://pubs.acs.org/doi/abs/10.1021/nn102492g},
  doi = {http://dx.doi.org/10.1021/nn102492g}
}
    Hongmei Liu, Zhenzhen Zhao, Nan Wang, Cui Yu & Jianwei Zhao Can the transition from tunneling to hopping in molecular junctions be predicted by theoretical calculation?

    [Abstract] [BibTeX]

    		 2011 J. Comput. Chem.
    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: molecular junction; theoretical simulation; electron tunneling; electron hopping; reorganization energy; ATK; Application
    Area: molecular electronics
    BibTeX: 
    @article{Liu2011b,
  author = {Liu, Hongmei and Zhao, Zhenzhen and Wang, Nan and Yu, Cui and Zhao, Jianwei},
  title = {Can the transition from tunneling to hopping in molecular junctions be predicted by theoretical calculation?},
  journal = {J. Comput. Chem.},
  publisher = {Wiley Subscription Services, Inc., A Wiley Company},
  year = {2011},
  volume = {32},
  number = {8},
  pages = {1687--1693},
  doi = {http://dx.doi.org/10.1002/jcc.21749}
}
    Cai-Juan Xia, Chang-Feng Fang, Peng Zhao & De-Sheng Liu Effect of torsion angle in 4,4'-biphenyldithiol functionalized molecular junction

    [Abstract] [BibTeX]

    		 2011 International Journal of Modern Physics B
    Vol. 25(5), 699-710     		 DOI  
    Abstract: Based on nonequilibrium Green's function and first-principles calculations, we investigate the electronic transport properties of 4,4'-biphenyldithiol functionalized molecular junction with different torsion angles between two phenyl rings. Numerical results show that torsion angle plays an important role in the conducting behavior of molecular junction. By changing the torsion angle, molecule can exhibit a switching behavior. Especially, when the molecule is functionalized with NO2 side group, it will perform a molecular memory effect. Furthermore, effects of different adsorption positions of sulfur atom on molecular memory are also discussed.
    Keywords: ATK; Application; Torsion angle; side group; electronic transport; molecular memory effect; molecular electronics
    Area: molecular electronics
    BibTeX: 
    @article{Xia2011e,
  author = {Xia, Cai-Juan and Fang, Chang-Feng and Zhao, Peng and Liu, De-Sheng},
  title = {Effect of torsion angle in 4,4'-biphenyldithiol functionalized molecular junction},
  journal = {International Journal of Modern Physics B},
  year = {2011},
  volume = {25},
  number = {5},
  pages = {699-710},
  doi = {http://dx.doi.org/10.1142/S0217979211058213}
}
    Shundong Yuan, Chunlei Dai, Jiena Weng, Qunbo Mei, Qidan Ling, Lianhui Wang & Wei Huang Theoretical Studies of Electron Transport in Thiophene Dimer: Effects of Substituent Group and Heteroatom

    [Abstract] [BibTeX]

    		 2011 The Journal of Physical Chemistry A
    Vol. 115(17), 4535-4546     		 DOI  
    Abstract: The electron-transport properties of various substituted molecules based on the thiol-ended thiophene dimer (2Th1DT) are investigated through density functional theory (DFT) combined with nonequilibrium Green's function (NEGF) method. The current-voltage (I-V) curves of all the Au/2Th1DT/Au systems in this work display similar steplike features, while their equilibrium conductances show a large difference and some of these I-V curves are asymmetric distinctly. The results reveal the dependence of conductance on the energy level of the substituted 2Th1DT molecules. Rectification ratios are computed to examine the asymmetric properties of the I-V curves. The rectifying behavior in the 2Th1DT molecule containing the amino group close to the molecular end is more prominent than that in the other molecules. The rectifying behavior is analyzed through transmission spectra and molecular projected self-consistent Hamiltonian (MPSH) states. Slight negative differential resistance (NDR) can be observed in some of the systems. The electron-transport properties of 2Th1DT molecules containing different heteroatoms are also investigated. The results indicate that the current in heteroatom-containing molecules is larger than that in their pristine analogues, and lighter heteroatoms are more favorable than heavier heteroatoms for electron transport of the thiophene dimer.
    Keywords: ATK; Application; molecular electronics; rectification; MPSH; NDR; negative differential resistance;
    Area: molecular electronics
    BibTeX: 
    @article{Yuan2011,
  author = {Yuan, Shundong and Dai, Chunlei and Weng, Jiena and Mei, Qunbo and Ling, Qidan and Wang, Lianhui and Huang, Wei},
  title = {Theoretical Studies of Electron Transport in Thiophene Dimer: Effects of Substituent Group and Heteroatom},
  journal = {The Journal of Physical Chemistry A},
  publisher = {American Chemical Society},
  year = {2011},
  volume = {115},
  number = {17},
  pages = {4535--4546},
  doi = {http://dx.doi.org/10.1021/jp201038f}
}
    Jiaxin Zheng, Xin Yan, Lili Yu, Hong Li, Rui Qin, Guangfu Luo, Zhengxiang Gao, Dapeng Yu & Jing Lu Family-Dependent Rectification Characteristics in Ultra-Short Graphene Nanoribbon p–n Junctions

    [Abstract] [BibTeX]

    		 2011 The Journal of Physical Chemistry C
    Vol. 115(17), 8547-8554     		 DOI  
    Abstract: We present the first transport property investigation of a-few-nanometer-long armchair graphene nanoribbon (AGNR) p-n junctions by using first-principles method. Intriguingly, family dependent rectification is observed. To be specific, traditional rectification effect in the forward direction is observed in the AGNR p-n junctions with 3n and 3n+2 widths, whereas reverse rectification effect is observed in the AGNR p-n junctions with 3n+1 width. The analysis of the spatial distribution of molecular projected self-consistent Hamiltonian eigenstates and the projected density of states give an insight into the observed results.
    Keywords: ATK; Application; graphene; p-n junction; rectification; MPSH
    Area: graphene
    BibTeX: 
    @article{Zheng2011,
  author = {Zheng, Jiaxin and Yan, Xin and Yu, Lili and Li, Hong and Qin, Rui and Luo, Guangfu and Gao, Zhengxiang and Yu, Dapeng and Lu, Jing},
  title = {Family-Dependent Rectification Characteristics in Ultra-Short Graphene Nanoribbon p–n Junctions},
  journal = {The Journal of Physical Chemistry C},
  publisher = {American Chemical Society},
  year = {2011},
  volume = {115},
  number = {17},
  pages = {8547--8554},
  doi = {http://dx.doi.org/10.1021/jp200982w}
}
    M. Zhou, Y.Q. Cai, M.G. Zeng, C. Zhang & Y.P. Feng Mn-doped thiolated Au[sub 25] nanoclusters: Atomic configuration, magnetic properties, and a possible high-performance spin filter

    [Abstract] [BibTeX]

    		 2011 Applied Physics Letters
    Vol. 98(14), 143103     		 DOI URL 
    Abstract: We report an ab inito investigation on the ground-state atomic configuration, electronic structures, magnetic, and spin-dependent transport properties of Mn-doped Au25 nanoclusters protected by thiolate. It is found that the most stable dopant sites are near surfaces, rather than the center position of the nanoparticles. Transport calculations show that high- performance spin filters can be achieved by sandwiching these doped clusters between two nonmagnetic Au electrodes. The nearly perfect spin filtering originates from localized magnetic moments of these clusters that are well protected by ligands from the presence of electrodes.
    Keywords: ab initio calculations; gold; ground states; magnetic moments; manganese; nanomagnetics; nanoparticles; spin dynamics; spin polarised transport; ATK; Application
    Area: molecular electronics; spin
    BibTeX: 
    @article{Zhou2011,
  author = {M. Zhou and Y. Q. Cai and M. G. Zeng and C. Zhang and Y. P. Feng},
  title = {Mn-doped thiolated Au[sub 25] nanoclusters: Atomic configuration, magnetic properties, and a possible high-performance spin filter},
  journal = {Applied Physics Letters},
  publisher = {AIP},
  year = {2011},
  volume = {98},
  number = {14},
  pages = {143103},
  url = {http://link.aip.org/link/?APL/98/143103/1},
  doi = {http://dx.doi.org/10.1063/1.3575203}
}
    Hui Fang, Ru-Zhi Wang, Si-Ying Chen, Mi Yan, Xue-Mei Song & Bo Wang Strain-induced negative differential resistance in armchair-edge graphene nanoribbons

    [Abstract] [BibTeX]

    		 2011 Applied Physics Letters
    Vol. 98(8), 082108     		 DOI  
    Abstract: The transport properties of graphene strips under tensile strain have been theoretically investigated. For the armchair-edge graphene nanoribbons (GNRs) with width N = 3m-1, the additional negative differential resistance (NDR) undergoes a process from occurring to enhancement and then disappearance with increasing tensile strain. The changes in the additional NDR may be originated from the suppression of strain-mediated channel states for the variations in degenerate energy bands near Fermi level. The strain-induced NDR behaviors of the GNRs present the possibility of the potential applications in electromechanical nanodevices such as stress-controlled Goto pair for digital signal restoration.
    Keywords: Fermi level; internal stresses; nanostructured materials; tensile strength; ATK; Application; ATK-SE; graphene nanoribbon; negative differential resistance; NDR;
    Area: graphene
    BibTeX: 
    @article{Fang2011,
  author = {Fang, Hui and Wang, Ru-Zhi and Chen, Si-Ying and Yan, Mi and Song, Xue-Mei and Wang, Bo},
  title = {Strain-induced negative differential resistance in armchair-edge graphene nanoribbons},
  journal = {Applied Physics Letters},
  publisher = {AIP},
  year = {2011},
  volume = {98},
  number = {8},
  pages = {082108},
  doi = {http://dx.doi.org/10.1063/1.3556637}
}
    Yongqing Cai, Miao Zhou, Minggang Zeng, Chun Zhang & Yuan Ping Feng Adsorbate and defect effects on electronic and transport properties of gold nanotubes

    [Abstract] [BibTeX]

    		 2011 Nanotechnology
    Vol. 22(21), 215702     		 DOI URL 
    Abstract: First-principles calculations have been performed to study the effects of adsorbates (CO molecules and O atoms) and defects on electronic structures and transport properties of Au nanotubes (Au(5, 3) and Au(5, 5)). For CO adsorption, various adsorption sites of CO on the Au tubes were considered. The vibrational frequency of the CO molecule was found to be very different for two nearly degenerate stable adsorption configurations of Au(5, 3), implying the possibility of distinguishing these two configurations via measuring the vibrational frequency of CO in experiments. After CO adsorption, the conductance of Au(5, 3) decreases by 0.9 G 0 and the conductance of Au(5, 5) decreases by approximately 0.5 G 0 . For O-adsorbed Au tubes, O atoms strongly interact with Au tubes, leading to around 2 G 0 of drop in conductance for both Au tubes. These results may have implications for Au-tube-based chemical sensing. When a monovacancy defect is present, we found that, for both tubes, the conductance decreases by around 1 G 0 . Another type of defect arising from the adhesion of one Au atom is also considered. For this case, it is found that, for the Au(5, 3) tube, the defect decreases the conductance by nearly 1 G 0 , whereas for Au(5, 5), the decrease in conductance is only 0.3 G 0 .
    Keywords: ATK; Application; gold nanotube; adsorbed molecules; vacancies
    Area: nanotubes
    BibTeX: 
    @article{Cai2011,
  author = {Yongqing Cai and Miao Zhou and Minggang Zeng and Chun Zhang and Yuan Ping Feng},
  title = {Adsorbate and defect effects on electronic and transport properties of gold nanotubes},
  journal = {Nanotechnology},
  year = {2011},
  volume = {22},
  number = {21},
  pages = {215702},
  url = {http://stacks.iop.org/0957-4484/22/i=21/a=215702},
  doi = {http://dx.doi.org/10.1088/0957-4484/22/21/215702}
}
    Qihang Liu, Lili Yu, Hong Li, Rui Qin, Zhou Jing, Jiaxin Zheng, Zhengxiang Gao & Jing Lu All-Metallic High-Performance Field Effect Transistor Based on Telescoping Carbon Nanotubes: An ab Initio Study

    [Abstract] [BibTeX]

    		 2011 The Journal of Physical Chemistry C
    Vol. 115(14), 6933-6938     		 DOI URL 
    Abstract: It has been well established that the electrical resistance of metal is insensitive to gate voltage and unsuitable for making field effect transistors. However, we find that telescoping pristine double-walled metallic carbon nanotubes are extremely sensitive to gate voltage with an on/off ratio up to 10,000 based on the first principles quantum transport calculations. This remarkable feature is closely related to the antiresonances in the transmission spectra. Besides, robust negative differential resistance effects are also found in the same device.
    Keywords: ATK; Application; field effect transistor; nanotube; NDR; negative differential resistance; telescoping tubes;
    Area: nanotubes
    BibTeX: 
    @article{Liu2011a,
  author = {Liu, Qihang and Yu, Lili and Li, Hong and Qin, Rui and Jing, Zhou and Zheng, Jiaxin and Gao, Zhengxiang and Lu, Jing},
  title = {All-Metallic High-Performance Field Effect Transistor Based on Telescoping Carbon Nanotubes: An ab Initio Study},
  journal = {The Journal of Physical Chemistry C},
  year = {2011},
  volume = {115},
  number = {14},
  pages = {6933-6938},
  url = {http://pubs.acs.org/doi/abs/10.1021/jp112285t},
  doi = {http://dx.doi.org/10.1021/jp112285t}
}
    CaiJuan Xia, DeSheng Liu & HanChen Liu A first-principles study of dihydroazulene as a possible optical molecular switch

    [Abstract] [BibTeX]

    		 2011 SCIENCE CHINA Physics, Mechanics & Astronomy
    Vol. 54(3), 437-441     		 DOI  
    Abstract: By applying nonequilibrium Green's function formalism combined with first-principles density functional theory, we investigate the electronic transport properties of the dihydroazulene optical molecular switch. Three kinds of adsorption sites including the hollow, bridge and top sites are studied. The two forms of this molecule, namely the open form and the closed form, can reversibly switch from each other upon photoexcitation. Their transmission spectra are remarkably distinctive. Theoretical results show that the current of the closed form is always significantly larger than that of the open form for all three adsorption sites, which promises this system as possibly one of the good candidates for optical switches due to its unique advantage, and which may have some potential applications in the future molecular circuit.
    Keywords: molecular electronics; ATK; Application; molecular switch, nonequilibrium Green's function; electronic transport; density functional theory
    Area: molecular electronics
    BibTeX: 
    @article{Xia2011b,
  author = {Xia, CaiJuan and Liu, DeSheng and Liu, HanChen},
  title = {A first-principles study of dihydroazulene as a possible optical molecular switch},
  journal = {SCIENCE CHINA Physics, Mechanics & Astronomy},
  publisher = {Science China Press, co-published with Springer},
  year = {2011},
  volume = {54},
  number = {3},
  pages = {437--441},
  doi = {http://dx.doi.org/10.1007/s11433-010-4233-5}
}
    CaiJuan Xia, HanChen Liu & QiuPing Wang An Ab Initio Study on Negative Differential Resistance in Pyrrole Trimer Molecular Device

    [Abstract] [BibTeX]

    		 2011 Advanced Materials Research
    Vol. 152-153, 931-934     		 DOI  
    Abstract: The electronic transport properties of pyrrole trimer sandwiched between two electrodes are investigated by using nonequilibrium Green's function formalism combined first-principles density functional theory. Theoretical results show that the system manifests negative differential resistance (NDR) behavior. A detailed analysis of the origin of negative differential resistance has been given by observing the shift in transmission resonance peak across the bias window with varying bias voltage.
    Keywords: ATK; Application; molecular device; NDR; negative differential resistance;
    Area: molecular electronics
    BibTeX: 
    @article{Xia2011c,
  author = {Xia, CaiJuan and Liu, HanChen and Wang, QiuPing},
  title = {An Ab Initio Study on Negative Differential Resistance in Pyrrole Trimer Molecular Device},
  journal = {Advanced Materials Research},
  year = {2011},
  volume = {152-153},
  pages = {931-934},
  doi = {http://dx.doi.org/10.4028/www.scientific.net/AMR.152-153.931}
}
    CaiJuan Xia, HanChen Liu & ChangFeng Fang The I-V Characteristics of the 3,3',5',5-Tetra-Tert-Butyl-Azobenzene Optical Molecular Switch: A First-Principles Study

    [Abstract] [BibTeX]

    		 2011 Advanced Materials Research
    Vol. 152-153, 839-842     		 DOI  
    Abstract: By applying nonequilibrium Green's function formalism combined first-principles density functional theory, we investigate the electronic transport properties of 3,3',5,5'-Tetra-tert-butyl-azobenzene(meta-TBA) optical molecular switch. This molecular switch comprises a meta-TBA molecule with the trans and cis forms, which can be reversed from one structure to another one 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 there is a large current ratio in bias window, which suggests that this system can be one of good candidates for optical switches due to this unique advantage, and have real applications in the molecular circuit.
    Keywords: ATK; Application; molecular switch; NDR; negative differential resistance; optical switch
    Area: molecular electronics
    BibTeX: 
    @article{Xia2011d,
  author = {Xia, CaiJuan and Liu, HanChen and Fang, ChangFeng},
  title = {The I-V Characteristics of the 3,3',5',5-Tetra-Tert-Butyl-Azobenzene Optical Molecular Switch: A First-Principles Study},
  journal = {Advanced Materials Research},
  year = {2011},
  volume = {152-153},
  pages = {839-842},
  doi = {http://dx.doi.org/10.4028/www.scientific.net/AMR.152-153.839}
}
    Guiling Zhang, Dong Li, Yan Shang, Hui Zhang, Miao Sun, Bo Liu & Zesheng Li Transport Properties of Double Quantum Dots Formed by Ferrocene Units

    [Abstract] [BibTeX]

    		 2011 The Journal of Physical Chemistry C
    Vol. 115(13), 5257-5264     		 DOI  
    Abstract: Combining nonequilibrium Green's function technique with density functional theory, the transport properties of a series of double quantum dots formed by ferrocene dimers with saturated carbon bridges and saturated silicon bridges, [Fc-(CH2)n]2 and [Fc-(SiH2)n]2 (n = 1,2,3), were comparatively studied. We have found that the type and the length of the bridge group between two adjacent ferrocene units plays an important role in governing the transport property. The negative differential resistance is enhanced with the lengthening of the space linker, i.e., the NDR magnitude follows the sequence of [Fc-(CH2)3]2 > [Fc-(CH2)2]2 > [Fc-CH2]2 and [Fc-(SiH2)3]2 > [Fc-(SiH2)2]2 > [Fc-SiH2]2. For the short bridged systems (n = 1,2), the conductivity of molecules with the carbon linkage is higher than that with the silicon linkage, that is, [Fc-CH2]2 > [Fc-SiH2]2 and [Fc-(CH2)2]2 > [Fc-(SiH2)2]2. In addition, [Fc-SiH2] presents a rectifier effect. The effect of the bridge on the transport property could be interpreted from the bonding, the molecular level state, the transmission spectrum, and the density of states.
    Keywords: ATK; Application; molecular electronics; ferrocene; quantum dots; negative differential resistance; NDR;
    Area: molecular electronics
    BibTeX: 
    @article{Zhang2011,
  author = {Zhang, Guiling and Li, Dong and Shang, Yan and Zhang, Hui and Sun, Miao and Liu, Bo and Li, Zesheng},
  title = {Transport Properties of Double Quantum Dots Formed by Ferrocene Units},
  journal = {The Journal of Physical Chemistry C},
  publisher = {American Chemical Society},
  year = {2011},
  volume = {115},
  number = {13},
  pages = {5257--5264},
  doi = {http://dx.doi.org/10.1021/jp1092064}
}
    Peng Zhao, De-Sheng Liu, Ying Zhang, Pei-Ji Wang & Zhong Zhang Rectifying Properties of a Nitrogen/Boron-Doped Capped-Carbon-Nanotube-Based Molecular Junction

    [Abstract] [BibTeX]

    		 2011 Chinese Physics Letters
    Vol. 28(4), 047301     		 DOI URL 
    Abstract: Based on the non-equilibrium Green's function method and first-principles density functional theory calculations, we investigate the electronic transport properties of a nitrogen/boron-doped capped-single-walled carbon-nanotube-based molecular junction. Obvious rectifying behavior is observed and it is strongly dependent on the doping site. The best rectifying performance can be carried out when the nitrogen/boron atom dopes at a carbon site in the second layer. Moreover, the rectifying performance can be further improved by adjusting the distance between the C 60 nanotube
    Keywords: ATK; Application; capped nanotube; carbon nanotube; rectification
    Area: nanotubes
    BibTeX: 
    @article{Zhao2011b,
  author = {Zhao, Peng and Liu, De-Sheng and Zhang, Ying and Wang, Pei-Ji and Zhang, Zhong},
  title = {Rectifying Properties of a Nitrogen/Boron-Doped Capped-Carbon-Nanotube-Based Molecular Junction},
  journal = {Chinese Physics Letters},
  year = {2011},
  volume = {28},
  number = {4},
  pages = {047301},
  url = {http://stacks.iop.org/0256-307X/28/i=4/a=047301},
  doi = {http://dx.doi.org/10.1088/0256-307X/28/4/047301}
}
    Larkhoon Leem, Ashutosh Srivastava, Shuang Li, Blanka Magyari-Köpe, Giuseppe Iannaccone, James Harris & Gianluca Fiori Multi-scale Simulations of Partially Unzipped CNT Hetero-junction Tunneling Field Effect Transistor

    [Abstract] [BibTeX]

    		 2010 2010 International Electron Devices Meeting - Technical Digest, 32.5.1-32.5.4  DOI  
    Abstract: Band-to-band Tunneling Field Effect Transistors (TFETs) are emerging as a solution to break classical 60mV/dec sub-threshold slope limit of conventional MOSFETs. In this work, we present for the first time multi-scale simulation results of partially unzipped Carbon Nanotube heterojunction TFET. Compared to the CNT and GNR homojunction TFETs, GNR/CNT heterojunction TFETs demonstrate superior sub-threshold region characteristics - 10(4)x smaller I-off, 61% smaller Subthreshold Swing (SS) which lies in the range of 22 similar to 26mV/dec and the I-V ambipolarity is completely eliminated.
    Keywords: MOSFET, carbon nanotubes, field effect transistors, semiconductor heterojunctions, tunnel transistors, tunnelling, heterojunction TFET, I-V ambipolarity, band-to-band tunneling field effect transistors, conventional MOSFET, multiscale simulation, sub-threshold slope limit, subthreshold region characteristics, subthreshold swing, graphene nanoribbon, ATK, Application
    Area: graphene; nanotubes
    BibTeX: 
    @inproceedings{Leem2010,
  author = {Leem, Larkhoon and Srivastava, Ashutosh and Li, Shuang and Magyari-Köpe, Blanka and Iannaccone, Giuseppe and Harris, James and Fiori, Gianluca},
  title = {Multi-scale Simulations of Partially Unzipped CNT Hetero-junction Tunneling Field Effect Transistor},
  booktitle = {2010 International Electron Devices Meeting - Technical Digest},
  publisher = {IEEE, 345 E 47th St, New York, NY 10017 USA},
  year = {2010},
  pages = {32.5.1--32.5.4},
  note = {International Electron Devices Meeting (IEDM), San Francisco, CA, DEC 06-08, 2010},
  doi = {http://dx.doi.org/10.1109/IEDM.2010.5703465}
}
    Xin Luo, Biao Wang & Yue Zheng Tunable Tunneling Electroresistance in Ferroelectric Tunnel Junctions by Mechanical Loads

    [Abstract] [BibTeX]

    		 2011 ACS Nano
    Vol. 5(3), 1649-1656     		 DOI  
    Abstract: Combining nonequilibrium Green function's approach with density functional theory, effects of the applied mechanical loads on polarization, electrostatic potential, and tunneling conductance of a ferroelectric tunneling junction (FTJ) have been investigated. Using the first principle calculations, we show that compressive strains can induce and enhance the polarization in ferroelectric tunnel barriers, and practically achieve ferroelectricity in two unit cell thickness under a -2.2% compressive strain. More importantly, mechanical strains can significantly change the effective electrostatic potential in FTJ and thus control its tunneling conductance, which is defined as giant piezoelectric resistance (GPR) effect. Our calculations indicate that GPR effect is particularly significant near the paraelectric/ferroelectric phase transition, and increases exponentially with the barrier thickness. Furthermore, it is also found that defects of oxygen vacancies and nitrogen doping have little impact on GPR ratio of strained FTJ. Because of its high-sensitivity to external mechanical loads, FTJ with GPR effect should be adequate for applications in agile mechanical sensors, transducers, and other multifunctional devices.
    Keywords: ATK; Application; ferroelectric tunneling junction; giant piezoelectric resistance; conductance; strain; phase transitionferroelectric tunneling junction; giant piezoelectric resistance; conductance; strain; phase transition
    Area: interfaces
    BibTeX: 
    @article{Luo2011,
  author = {Luo, Xin and Wang, Biao and Zheng, Yue},
  title = {Tunable Tunneling Electroresistance in Ferroelectric Tunnel Junctions by Mechanical Loads},
  journal = {ACS Nano},
  publisher = {American Chemical Society},
  year = {2011},
  volume = {5},
  number = {3},
  pages = {1649--1656},
  doi = {http://dx.doi.org/10.1021/nn1031438}
}
    J.B. Pan, Z.H. Zhang, K.H. Ding, X.Q. Deng & C. Guo Current rectification induced by asymmetrical electrode materials in a molecular device

    [Abstract] [BibTeX]

    		 2011 Applied Physics Letters
    Vol. 98(9), 092102     		 DOI  
    Abstract: Molecular devices are constructed based on a molecule connected into both electrodes with different metal materials, and their transport properties are investigated by the first-principles method. The result shows that such devices can generate two asymmetrical Schottky barriers at contacts; the current rectification thus is created. This rectification is also fully rationalized by the calculated transmission spectra and the spatial distribution of the lowest unoccupied molecular orbital and highest occupied molecular orbital states. Our study suggests that it might be a very important way for both electrodes using different materials to realize a molecular rectification.
    Keywords: ATK; Application; molecular electronics; asymmetrical Schottky barriers; rectification;
    Area: molecular electronics
    BibTeX: 
    @article{Pan2011,
  author = {Pan, J. B. and Zhang, Z. H. and Ding, K. H. and Deng, X. Q. and Guo, C.},
  title = {Current rectification induced by asymmetrical electrode materials in a molecular device},
  journal = {Applied Physics Letters},
  year = {2011},
  volume = {98},
  number = {9},
  pages = {092102},
  doi = {http://dx.doi.org/10.1063/1.3556278}
}
    Zhongchang Wang, Masaki Okude, Mitsuhiro Saito, Susumu Tsukimoto, Akira Ohtomo, Masaru Tsukada, Masashi Kawasaki & Yuichi Ikuhara Dimensionality-driven insulator-metal transition in A-site excess non-stoichiometric perovskites

    [Abstract] [BibTeX]

    		 2010 Nature Communications
    Vol. 1(8), 106     		 DOI  
    Abstract: Coaxing correlated materials to the proximity of the insulator-metal transition region, where electronic wavefunctions transform from localized to itinerant, is currently the subject of intensive research because of the hopes it raises for technological applications and also for its fundamental scientific significance. In general, this tuning is achieved by either chemical doping to introduce charge carriers, or external stimuli to lower the ratio of Coulomb repulsion to bandwidth. In this study, we combine experiment and theory to show that the transition from well-localized insulating states to metallicity in a Ruddlesden-Popper series, La(0.5)Sr(n+1-0.5)Ti(n)O(3n+1), is driven by intercalating an intrinsically insulating SrTiO3 unit, in structural terms, by dimensionality n. This unconventional strategy, which can be understood upon a complex interplay between electron-phonon coupling and electron correlations, opens up a new avenue to obtain metallicity or even superconductivity in oxide superlattices that are normally expected to be insulators.
    Keywords: ATK; Application; metal-insulator junction; superconductivity; metallicity; oxide superlattices; SrTiO3;
    Area: interfaces
    BibTeX: 
    @article{Wang2010d,
  author = {Wang, Zhongchang and Okude, Masaki and Saito, Mitsuhiro and Tsukimoto, Susumu and Ohtomo, Akira and Tsukada, Masaru and Kawasaki, Masashi and Ikuhara, Yuichi},
  title = {Dimensionality-driven insulator-metal transition in A-site excess non-stoichiometric perovskites},
  journal = {Nature Communications},
  publisher = {Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.},
  year = {2010},
  volume = {1},
  number = {8},
  pages = {106},
  doi = {http://dx.doi.org/10.1038/ncomms1111}
}
    Xiaojun Wu, Rulong Zhou, Jinlong Yang & Xiao Cheng Zeng Density-Functional Theory Studies of Step-Kinked Carbon Nanotubes

    [Abstract] [BibTeX]

    		 2011 The Journal of Physical Chemistry C
    Vol. 115(10), 4235-4239     		 DOI  
    Abstract: Using density-functional theory (DFT) methods, we investigate structural, electronic, and transport properties of step-kinked single-walled carbon nanotubes (SWCNT). To devise a sensible model for the joint section of the kinked nanotube, we examine relative stability of two (6,0) carbon-nanotube-based C672 isomers, namely, a carbon nanoring and a carbon hexagonal nanotorus. We find that the hexagonal nanotorus C672 is energetically more favorable than the isomeric nanoring (i.e., circular nanotorus) C672. By use of the kinked section of the hexagonal nanotorus as a model joint, the periodic step-kinked carbon nanotubes can be built. According to the DFT calculation using the hybrid B3LYP functional, we find that introduction of the periodic kinks turns the perfect (5,0) SWCNT with zero band gap ( J. Phys. Chem. Lett. 2010, 1, 2946) into a semiconductor with a band gap 0.76 eV. In contrast, the step-kinked (6,0) SWCNT is still a metal with zero band gap, like the perfect (6,0) SWCNT. We also compare the electronic transport properties of a perfect (5,0) SWCNT with the step-kinked (5,0) SWCNT. The former has a nonzero steplike electron transmission distribution near the Fermi level, while the latter shows some sharp transmission peaks around the Fermi level.
    Keywords: ATK; Application; nanotube; nanotorus; transport properties:
    Area: nanotubes
    BibTeX: 
    @article{Wu2011,
  author = {Wu, Xiaojun and Zhou, Rulong and Yang, Jinlong and Zeng, Xiao Cheng},
  title = {Density-Functional Theory Studies of Step-Kinked Carbon Nanotubes},
  journal = {The Journal of Physical Chemistry C},
  publisher = {American Chemical Society},
  year = {2011},
  volume = {115},
  number = {10},
  pages = {4235--4239},
  doi = {http://dx.doi.org/10.1021/jp110717k}
}
    Minggang Zeng, Lei Shen, Ming Yang, Chun Zhang & Yuanping Feng Feng Charge and spin transport in graphene-based heterostructure

    [Abstract] [BibTeX]

    		 2011 Applied Physics Letters
    Vol. 98(5), 053101-3     		 DOI  
    Abstract: We investigate electron transport properties of a heterostructure based on zigzag graphene nanoribbon (ZGNR) by first-principles calculations. This heterostructure consists of hydrogen-terminated ZGNR (ZGNR-H) and oxygen-terminated ZGNR (ZGNR-O). We find that both charge and spin transport can be well controlled with the ZGNR-H/ZGNR-O heterostructure. A large charge transmission gap appears near the Fermi energy, and rectification behavior is observed. Moreover, the ZGNR-H/ZGNR-O heterostructure can act as a perfect bipolar spin filter or magnetoresistance device. Our results show that the ZGNR-H/ZGNR-O heterostructure hold promise for combining magnetoelectronics and conventional charge-based electronics.
    Keywords: ab initio calculations, density functional theory, Fermi level, giant magnetoresistance, graphene, Green's function methods, hydrogen, nanostructured materials, oxygen, rectification, ATK, Application, spin
    Area: graphene; spin
    BibTeX: 
    @article{Zeng2011b,
  author = {Zeng, Minggang and Shen, Lei and Yang, Ming and Zhang, Chun and Feng, Yuanping Feng},
  title = {Charge and spin transport in graphene-based heterostructure},
  journal = {Applied Physics Letters},
  year = {2011},
  volume = {98},
  number = {5},
  pages = {053101--3},
  doi = {http://dx.doi.org/10.1063/1.3549154}
}
    Minggang Zeng, Yuanping Feng & Gengchiau Liang Graphene-based Spin Caloritronics

    [Abstract] [BibTeX]

    		 2011 Nano Letters
    Vol. 11(3), 1369-1373     		 DOI  
    Abstract: Thermally induced spin transport in magnetized zigzag graphene nanoribbons (M-ZGNRs) is explored using first-principles calculations. By applying temperature difference between the source and the drain of a M-ZGNR device, spin-up and spin-down currents flowing in opposite directions can be induced. This spin Seebeck effect in M-ZGNRs can be attributed to the asymmetric electron-hole transmission spectra of spin-up and spin-down electrons. Furthermore, these spin currents can be modulated and completely polarized by tuning the back gate voltage. Finally, thermal magnetoresistance of ZGNRs between ground states and magnetized states can reach 104% without an external bias. Our results indicate the possibility of developing graphene-based spin caloritronic devices.
    Keywords: ATK; Application; graphene; spin caloritronics; spintronics; spin Seebeck effect; thermal magnetoresistance effect; thermal spin components
    Area: graphene; spin
    BibTeX: 
    @article{Zeng2011c,
  author = {Zeng, Minggang and Feng, Yuanping and Liang, Gengchiau},
  title = {Graphene-based Spin Caloritronics},
  journal = {Nano Letters},
  publisher = {American Chemical Society},
  year = {2011},
  volume = {11},
  number = {3},
  pages = {1369--1373},
  doi = {http://dx.doi.org/10.1021/nl2000049}
}
    Jing Zhou, Xin Yan, Guangfu Luo, Rui Qin, Hong Li, Jing Lu, Wai Ning Mei & Zhengxiang Gao Structural, Electronic, and Transport Properties of Gd/Eu Atomic Chains Encapsulated in Single-Walled Carbon Nanotubes

    [Abstract] [BibTeX]

    		 2010 The Journal of Physical Chemistry C
    Vol. 114(36), 15347-15353     		 DOI  
    Abstract: Structural, electronic, and transport properties of Gd/Eu atomic chains encapsulated in single-walled carbon nanotubes (SWCNTs) are studied by using first-principles density functional theory and the nonequilibrium Green's function method. We find that the linear single-atom Gd and Eu chains occupy an off-centered position when encapsulated in the (8,0), (10,0), and (6,6) SWCNTs and considerable electrons are transferred from the Gd and Eu chains to the SWCNTs. The resulting composites are all ferromagnetic metals, with the conductivity significantly larger than those of the pristine SWCNTs and the free-standing Gd/Eu linear single-atom atomic chains. The spin polarization of the finite Gd linear single-atom chain at the Fermi level is 67% when encapsulated in the (8,0) SWCNT from the quantum transport calculation.
    Keywords: atomic chains; rare earth elements; carbon nanotubes; electron transfer; ATK; Application; spin
    Area: nanotubes; spin
    BibTeX: 
    @article{Zhou2010b,
  author = {Zhou, Jing and Yan, Xin and Luo, Guangfu and Qin, Rui and Li, Hong and Lu, Jing and Mei, Wai Ning and Gao, Zhengxiang},
  title = {Structural, Electronic, and Transport Properties of Gd/Eu Atomic Chains Encapsulated in Single-Walled Carbon Nanotubes},
  journal = {The Journal of Physical Chemistry C},
  publisher = {American Chemical Society},
  year = {2010},
  volume = {114},
  number = {36},
  pages = {15347--15353},
  doi = {http://dx.doi.org/10.1021/jp105274v}
}
    H. Sahin, R.T. Senger & S. Ciraci Spintronic properties of zigzag-edged triangular graphene flakes

    [Abstract] [BibTeX]

    		 2010 J. Appl. Phys.
    Vol. 108(7), 074301-5     		 DOI URL 
    Abstract: We investigate quantum transport properties of triangular graphene flakes with zigzag edges by using first principles calculations. Triangular graphene flakes have large magnetic moments which vary with the number of hydrogen atoms terminating its edge atoms and scale with its size. Electronic transmission and current-voltage characteristics of these flakes, when contacted with metallic electrodes, reveal spin valve and remarkable rectification features. The transition from ferromagnetic to antiferromagnetic state under bias voltage can, however, terminate the spin polarizing effects for specific flakes. Geometry and size dependent transport properties of graphene flakes may be crucial for spintronic nanodevice applications.
    Keywords: ab initio calculations, antiferromagnetic materials, ferromagnetic materials, ferromagnetic-antiferromagnetic transitions, graphene, hydrogen neutral atoms, magnetic moments, magnetoelectronics, spin polarised transport, spin valves, ATK, Application
    Area: graphene
    BibTeX: 
    @article{Sahin2010,
  author = {Sahin, H. and Senger, R. T. and Ciraci, S.},
  title = {Spintronic properties of zigzag-edged triangular graphene flakes},
  journal = {J. Appl. Phys.},
  publisher = {AIP},
  year = {2010},
  volume = {108},
  number = {7},
  pages = {074301--5},
  url = {http://link.aip.org/link/?JAP/108/074301/1},
  doi = {http://dx.doi.org/10.1063/1.3489919}
}
    Zhenxiang Dai, Argo Nurbawono, Aihua Zhang, Miao Zhou, Yuan Ping Feng, Ghim Wei Ho & Chun Zhang C-doped ZnO nanowires: Electronic structures, magnetic properties, and a possible spintronic device

    [Abstract] [BibTeX]

    		 2011 J. Chem. Phys.
    Vol. 134(10), 104706-5     		 DOI URL 
    Abstract: Electronic structures, magnetic properties, and spin-dependent electron transport characteristics of C-doped ZnO nanowires have been investigated via first-principles method based on density functional theory and nonequilibrium techniques of Green's functions. Our calculations show that the doping of carbon atoms in a ZnO nanowire could induce strong magnetic moments in the wire, and the electronic structures as well as the magnetic properties of the system sensitively depend on partial hydrogenation. Based on these findings, we proposed a quasi-1d tunneling magnetic junction made of a partially hydrogenated C-doped ZnO nanowire, which shows a high tunneling magnetoresistance ratio, and could be the building block of a new class of spintronic devices.
    Keywords: ab initio calculations, density functional theory, energy gap, Green's function methods, hydrogenation, II-VI semiconductors, magnetic moments, nanomagnetics, nanowires, semiconductor quantum wires, semimagnetic semiconductors, spin polarised transport, tunnelling magnetoresistance, wide band gap semiconductors, zinc compounds, ATK, Application
    Area: nanowires, spin
    BibTeX: 
    @article{Dai2011,
  author = {Dai, Zhenxiang and Nurbawono, Argo and Zhang, Aihua and Zhou, Miao and Feng, Yuan Ping and Ho, Ghim Wei and Zhang, Chun},
  title = {C-doped ZnO nanowires: Electronic structures, magnetic properties, and a possible spintronic device},
  journal = {J. Chem. Phys.},
  publisher = {AIP},
  year = {2011},
  volume = {134},
  number = {10},
  pages = {104706--5},
  url = {http://link.aip.org/link/?JCP/134/104706/1},
  doi = {http://dx.doi.org/10.1063/1.3562375}
}
    Nengyue Gao, Hongmei Liu, Cui Yu, Nan Wang, Jianwei Zhao & Hongfeng Xie Asymmetric electron transport through a conjugated-saturated hydrocarbon molecular wire

    [Abstract] [BibTeX]

    		 2011 Computational and Theoretical Chemistry
    Vol. 963(1), 55-62     		 DOI URL 
    Abstract: To understand the barrier effect on the asymmetric electron transport, we have employed a series of hybrid molecular junctions composed of conjugated and saturated hydrocarbon chains. The length of molecular wire is fixed, while the ratio of conjugated and saturated chains varies. In each model, the current-voltage characteristics have been studied using the first-principles density functional theory in conjunction with the non-equilibrium Green's function method. We found that the rectification performance is correlated to the barrier length. The mechanism of this phenomenon is related to the asymmetric coupling between the conjugated moiety and the metallic electrode.
    Keywords: Molecular rectification; Electron transport; Molecular junction; Electrode-molecule coupling; Barrier length; ATK; Application
    Area: molecular electronics
    BibTeX: 
    @article{Gao2011,
  author = {Gao, Nengyue and Liu, Hongmei and Yu, Cui and Wang, Nan and Zhao, Jianwei and Xie, Hongfeng},
  title = {Asymmetric electron transport through a conjugated-saturated hydrocarbon molecular wire},
  journal = {Computational and Theoretical Chemistry},
  year = {2011},
  volume = {963},
  number = {1},
  pages = {55--62},
  url = {http://www.sciencedirect.com/science/article/B6KFD-5172701-6/2/5ddfc7eb43ff356153c84d98129a63b1},
  doi = {http://dx.doi.org/10.1016/j.comptc.2010.09.008}
}
    Guomin Ji, Yaxin Zhai, Changfeng Fang, Yuqing Xu, Bin Cui & Desheng Liu The electronic transport properties in C60 molecular devices with different contact distances

    [Abstract] [BibTeX]

    		 2011 Physics Letters A
    Vol. 375(14), 1602-1607     		 DOI URL 
    Abstract: By applying non-equilibrium Green's functions in combination with the density-functional theory, we investigate the transport behavior of molecular devices composed by metal electrode-C60 molecule-metal electrode. Our results show that the electronic transport properties are affected obviously by the different contact distances between the electrodes, and the tunneling current decreases approximately exponentially at a certain bias with the increasing of contact distances. The negative differential resistance is observed and the peak-to-valley ratio can be tuned by different contact distances. The mechanisms of the contact distance effect and the negative differential resistance behavior are proposed.
    Keywords: ATK; Application; Negative differential resistance; NDR; fullerene; molecular electronics; molecular device
    Area: molecular electronics
    BibTeX: 
    @article{Ji2011,
  author = {Ji, Guomin and Zhai, Yaxin and Fang, Changfeng and Xu, Yuqing and Cui, Bin and Liu, Desheng},
  title = {The electronic transport properties in C60 molecular devices with different contact distances},
  journal = {Physics Letters A},
  year = {2011},
  volume = {375},
  number = {14},
  pages = {1602--1607},
  url = {http://www.sciencedirect.com/science/article/B6TVM-52966TY-3/2/5105656ff4b2940ba08ee728c19b2659},
  doi = {http://dx.doi.org/10.1016/j.physleta.2011.02.058}
}
    Kai-Tak Lam, Yunhao Lu, Yuan Ping Feng & Gengchiau Liang Stability and electronic structure of two dimensional C[sub x](BN)[sub y] compound

    [Abstract] [BibTeX]

    		 2011 Appl. Phys. Lett.
    Vol. 98(2), 022101-3     		 DOI URL 
    Abstract: The thermal stability and electronic structures of two dimensional Cx(BN)y compounds are studied using first-principles calculations based on the density functional theory. Although, from total energy calculations, it was well-established that phase-segregated atomic arrangements had the lowest energy, we found that due to the high activation energy required for phase-segregation process, evenly distributed configurations are stable at room temperature. Furthermore, the energy bandgap of the evenly distributed Cx(BN)y compounds is dependent on the carbon concentration. By controlling the carbon concentration in the compound, the EG of the compound
    material can be adjusted for electronic applications.
    Keywords: reaction path; ab initio calculations; carbon compounds; boron nitride; density functional theory; energy gap; segregation; thermal stability; total energy; ATK; Application
    Area: graphene
    BibTeX: 
    @article{Lam2011,
  author = {Lam, Kai-Tak and Lu, Yunhao and Feng, Yuan Ping and Liang, Gengchiau},
  title = {Stability and electronic structure of two dimensional C[sub x](BN)[sub y] compound},
  journal = {Appl. Phys. Lett.},
  publisher = {AIP},
  year = {2011},
  volume = {98},
  number = {2},
  pages = {022101--3},
  url = {http://link.aip.org/link/?APL/98/022101/1},
  doi = {http://dx.doi.org/10.1063/1.3535604}
}
    Enling Li, Xiqiang Wang, Liping Hou, Danna Zhao, Yuanbin Dai & Xuewen Wang Study on the Electronic Transport Properties of Zigzag GaN Nanotubes

    [Abstract] [BibTeX]

    		 2011 Journal of Physics: Conference Series
    Vol. 276(1), 012046     		 DOI URL 
    Abstract: The electronic transport properties of zigzag GaN nanotubes (n, 0) (4<=n<=9) have been calculated using the density functional theory and non-equilibrium Green's functions method. Firstly, the density functional theory (DFT) is used to optimize and calculate the electronic structure of GaNNTs (n, 0) (4<=n<=9). Secondly, DFT and non-equilibrium Green function (NEGF) method are also used to predict the electronic transport properties of GaNNTs two-probe system. The results showed: there is a corresponding relation between the electronic transport properties and the valley of state density of each GaNNT. In addition, the volt-ampere curve of GaNNT is approximately linear.
    Keywords: ATK; Application; GaN; nanotubes;
    Area: nanotubes
    BibTeX: 
    @article{Li2011,
  author = {Li, Enling and Wang, Xiqiang and Hou, Liping and Zhao, Danna and Dai, Yuanbin and Wang, Xuewen},
  title = {Study on the Electronic Transport Properties of Zigzag GaN Nanotubes},
  journal = {Journal of Physics: Conference Series},
  year = {2011},
  volume = {276},
  number = {1},
  pages = {012046},
  url = {http://stacks.iop.org/1742-6596/276/i=1/a=012046},
  doi = {http://dx.doi.org/10.1088/1742-6596/276/1/012046}
}
    Ling-Na Chen, Song-Shan Ma, Fang-Ping OuYang, Jin Xiao & Hui Xu First-principles study of metallic carbon nanotubes with boron/nitrogen co-doping

    [Abstract] [BibTeX]

    		 2011 Chinese Physics B
    Vol. 20(1), 017103     		 DOI URL 
    Abstract: Using the first-principles calculations, we investigate the electronic band structure and the quantum transport properties of metallic carbon nanotubes (MCNTs) with B/N pair co-doping. The results about formation energy show that the B/N pair co-doping configuration is a most stable structure. We find that the electronic structure and the transport properties are very sensitive to the doping concentration of the B/N pairs in MCNTs, where the energy gaps increase with doping concentration increasing both along the tube axis and around the tube, because the mirror symmetry of MCNT is broken by doping B/N pairs. In addition, we discuss conductance dips of the transmission spectrum of doped MCNTs. These unconventional doping effects could be used to design novel nanoelectronic devices.
    Keywords: ATK; Application; nanotube; doping
    Area: nanotubes
    BibTeX: 
    @article{LingNa2011,
  author = {Chen, Ling-Na and Ma, Song-Shan and OuYang, Fang-Ping and Xiao, Jin and Xu, Hui},
  title = {First-principles study of metallic carbon nanotubes with boron/nitrogen co-doping},
  journal = {Chinese Physics B},
  year = {2011},
  volume = {20},
  number = {1},
  pages = {017103},
  url = {http://stacks.iop.org/1674-1056/20/i=1/a=017103},
  doi = {http://dx.doi.org/10.1088/1674-1056/20/1/017103}
}
    Minggang Zeng, Lei Shen, Miao Zhou, Chun Zhang & Yuanping Feng Graphene-based bipolar spin diode and spin transistor: Rectification and amplification of spin-polarized current

    [Abstract] [BibTeX]

    		 2011 Phys. Rev. B
    Vol. 83(11), 115427     		 DOI  
    Abstract: Using nonequilibrium Green's function method combined with density functional theory we report bipolar spin diode behavior in zigzag graphene nanoribbons (ZGNRs). Nearly ±100% spin-polarized current can be generated and tuned by a source-drain voltage and/or magnetic configurations in these two-terminal bipolar spin diodes. This unique transport property is attributed to the intrinsic transmission selection rule of the wave function of spin subbands near the Fermi level in ZGNRs. Moreover, the bias voltage and magnetic configurations of the two-terminal ZGNR-based spin diodes provide a rich variety of ways to control the spin current, which can be used to design three-terminal spin transistors. These ZGNRs-based components make possible the manipulation of spin-polarized current such as rectification and amplification for carbon-based spintronics.
    Keywords: ATK; Application; graphene; spin; bipolar; diode; rectification
    Area: graphene; spin
    BibTeX: 
    @article{Zeng2011,
  author = {Zeng, Minggang and Shen, Lei and Zhou, Miao and Zhang, Chun and Feng, Yuanping},
  title = {Graphene-based bipolar spin diode and spin transistor: Rectification and amplification of spin-polarized current},
  journal = {Phys. Rev. B},
  publisher = {American Physical Society},
  year = {2011},
  volume = {83},
  number = {11},
  pages = {115427},
  doi = {http://dx.doi.org/10.1103/PhysRevB.83.115427}
}
    Minggang Zeng, Lei Shen, Haibin Su, Chun Zhang & Yuanping Feng Graphene-based spin logic gates

    [Abstract] [BibTeX]

    		 2011 Applied Physics Letters
    Vol. 98(9), 092110-3     		 DOI URL 
    Abstract: Logic operation is the key of digital electronics and spintronics. Based on spin-dependent transport property of zigzag graphene nanoribbons studied using nonequilibrium Green's function method and density functional theory, we propose a complete set of all-carbon spin logic gates, in which the spin-polarized current can be manipulated by the source-drain voltage and magnetic configuration of the electrodes. These logic gates allow further designs of complex spin logic operations and pave the way for full implementation of spintronics computing devices.
    Keywords: density functional theory, electrodes, graphene, Green's function methods, logic gates, magnetoelectronics, nanostructured materials, spin polarised transport, ATK, Application
    Area: graphene; spin
    BibTeX: 
    @article{Zeng2011a,
  author = {Zeng, Minggang and Shen, Lei and and Su, Haibin and Zhang, Chun and Feng, Yuanping},
  title = {Graphene-based spin logic gates},
  journal = {Applied Physics Letters},
  publisher = {AIP},
  year = {2011},
  volume = {98},
  number = {9},
  pages = {092110--3},
  url = {http://link.aip.org/link/?APL/98/092110/1},
  doi = {http://dx.doi.org/10.1063/1.3562320}
}
    Aiko Fukazawa, Manabu Kiguchi, Satoshi Tange, Yasunori Ichihashi, Qiang Zhao, Takuya Takahashi, Tatsuya Konishi, Kei Murakoshi, Yuta Tsuji, Aleksandar Staykov, Kazunari Yoshizawa & Shigehiro Yamaguchi Phosphine Sulfides as an Anchor Unit for Single Molecule Junctions

    [Abstract] [BibTeX]

    		 2011 Chemistry Letters
    Vol. 40(2), 174-176     		 DOI  
    Abstract: Phenylene and biphenyl compounds with dibenzophosphole sulfide (DBPS) as an anchoring group for single molecule junctions were synthesized. The conductance measurements revealed that the phosphine sulfide indeed acts as an anchoring group for Au electrodes. Theoretical calculations including metal electrodes demonstrated that the LUMO level of the DBPS-terminated biphenyl is close to the Au Fermi level, leading to the electron conduction of the Au-molecule-Au junction based on the resonance-tunneling mechanism.
    Keywords: molecular electronics; ATK; Application; single molecule junction;
    Area: molecular electronics
    BibTeX: 
    @article{Fukazawa2011,
  author = {Fukazawa, Aiko and Kiguchi, Manabu and Tange, Satoshi and Ichihashi, Yasunori and Zhao, Qiang and Takahashi, Takuya and Konishi, Tatsuya and Murakoshi, Kei and Tsuji, Yuta and Staykov, Aleksandar and Yoshizawa, Kazunari and Yamaguchi, Shigehiro},
  title = {Phosphine Sulfides as an Anchor Unit for Single Molecule Junctions},
  journal = {Chemistry Letters},
  year = {2011},
  volume = {40},
  number = {2},
  pages = {174--176},
  doi = {http://dx.doi.org/10.1246/cl.2011.174}
}
    Qin Han, Bing Cao, Liping Zhou, Guiju Zhang & Zhenghui Liu Electrical Transport Study of Single-Walled ZnO Nanotubes: A First-Principles Study of the Length Dependence

    [Abstract] [BibTeX]

    		 2011 The Journal of Physical Chemistry C
    Vol. 115(8), 3447-3452     		 DOI  
    Abstract: The electronic transport properties are characterized for single-walled zigzag (9, 0) ZnO nanotubes sandwiched between two lithium electrodes using a combined nonequilibrium Green's function and DFT-based formalism. By applying different bias voltages, the current-voltage characteristics are calculated for nanotubes of different lengths. The results indicate that the conductance of the system decreases exponentially with the increased length of the nanotubes. Metallic behavior is predicted for very short nanotubes, which is caused by the interface states from the metal-nanotubes interface. For longer nanotubes, the effect of the interface becomes smaller with the increased lengths. And semiconductor-like behaviors are observed, which are mainly determined by the ZnO nanotubes themselves. In addition, a peculiar phenomenon is observed that the values of the current at high bias are insensitive to the lengths. The behaviors can be understood in terms of the transmission spectrum, which shows that the transport properties are dominated by the electron states above the Fermi energy.
    Keywords: ZnO; nanotubes; ATK; Application;
    Area: nanotubes
    BibTeX: 
    @article{Han2011,
  author = {Han, Qin and Cao, Bing and Zhou, Liping and Zhang, Guiju and Liu, Zhenghui},
  title = {Electrical Transport Study of Single-Walled ZnO Nanotubes: A First-Principles Study of the Length Dependence},
  journal = {The Journal of Physical Chemistry C},
  publisher = {American Chemical Society},
  year = {2011},
  volume = {115},
  number = {8},
  pages = {3447--3452},
  doi = {http://dx.doi.org/10.1021/jp1089917}
}
    Aleksandar Staykov, Yuta Tsuji & Kazunari Yoshizawa Conductance through Short DNA Molecules

    [Abstract] [BibTeX]

    		 2011 The Journal of Physical Chemistry C
    Vol. 115(8), 3481-3490     		 DOI  
    Abstract: The conductance through short DNA molecules connected to gold electrodes is studied with density functional theory and nonequilibrium Green's function method combined with density functional theory. The anchoring of the molecules to the electrodes is investigated, and in addition to the covalent S-Au bond, weak interactions between the aromatic heterocyclic bases and the electrodes are found. These weak interactions are important for the electron transport through DNA molecules. A tunneling mechanism is suggested, and the conductive properties of the nucleotides in a metal-molecule-metal junction are compared. Different four-nucleotide DNA sequences are investigated. A significant value for the current, 20 pA, is calculated for 1.5 V applied bias for a DNA sequence consisting of guanine and cytosine nucleotides. It is shown that adenine-thymine nucleotide pairs introduce potential barriers for the electron transport and therefore significantly decline the conductance. The obtained results are compared with recent experimental observations (Nanotechnology2009, 20, 115502) and confirm the possibility for electron transport through DNA molecules as well as provide an explanation for the reduced conductance through DNA sequences, which contain adenine-thymine nucleotide pairs. The results are compared with a previous theoretical study, performed with the extended Hückel method (ChemPhysChem2003, 4, 1256), which reports low conductance for DNA molecules. The difference in the conclusions is due to the applied bias self-consistent field calculations used in the recent study, which take into account the changes of the transmission probabilities with the bias.
    Keywords: ATK; Application; molecular electronics; DNA;
    Area: molecular electronics
    BibTeX: 
    @article{Staykov2011,
  author = {Staykov, Aleksandar and Tsuji, Yuta and Yoshizawa, Kazunari},
  title = {Conductance through Short DNA Molecules},
  journal = {The Journal of Physical Chemistry C},
  publisher = {American Chemical Society},
  year = {2011},
  volume = {115},
  number = {8},
  pages = {3481--3490},
  doi = {http://dx.doi.org/10.1021/jp110803a}
}
    Cai-Juan Xia, De-Sheng Liu, Han-Chen Liu & Ying-Tang Zhang A possible salicylideneanilines-based optical molecular switch induced by a reversible hydrogen transfer: an ab initio study

    [Abstract] [BibTeX]

    		 2011 Molecular Physics: An International Journal at the Interface Between Chemistry and Physics
    Vol. 109(2), 209-215     		 DOI  
    Abstract: The electronic transport properties of the salicylideneanilines-based molecular optical switch are investigated using a nonequilibrium Green's function formalism combined with first-principles density functional theory. The molecule that comprises the switch can convert between the enol and keto tautomeric forms upon photoinduced excited state hydrogen transfer in the molecular bridge. Theoretical results show that the current through the enol form is significantly larger than that through the keto form, which realize the on and off states of the molecular switch. The physical origin of the switching behaviour is interpreted based on the spatial distributions of molecular orbitals and the HOMO-LUMO gap. Furthermore the effect of the donor/acceptor substituent on the electronic transport through the molecular device is also discussed in detail. The switching performance can be improved to some extent through the acceptor substituent.
    Keywords: ATK; Application; molecular switch; nonequilibrium Green's function; electronic transport; density functional theory; molecular electronics
    Area: molecular electronics
    BibTeX: 
    @article{Xia2011,
  author = {Xia, Cai-Juan and Liu, De-Sheng and Liu, Han-Chen and Zhang, Ying-Tang},
  title = {A possible salicylideneanilines-based optical molecular switch induced by a reversible hydrogen transfer: an ab initio study},
  journal = {Molecular Physics: An International Journal at the Interface Between Chemistry and Physics},
  publisher = {Taylor & Francis},
  year = {2011},
  volume = {109},
  number = {2},
  pages = {209--215},
  doi = {http://dx.doi.org/10.1080/00268976.2010.515255}
}
    Bidisa Das & Molly De Raychaudhury Electronic structure and transport properties of early transition metal tripledeckers

    [Abstract] [BibTeX]

    		 2011 Journal of Chemical Physics
    Vol. 134(1), 014709-10     		 DOI URL 
    Abstract: The electronic structure and transport properties of the Cp2BzM2 (M = Sc, Ti, and V) tripledeckers are studied by spin polarized density functional theory and nonequilibrium Green's function method considering high-spin and low-spin states. Total energy calculations show that the sandwich structured Cp2BzSc2 exists in a singlet state with no local magnetic moment on the Sc atoms. Cp2BzTi2 in triplet state exists as a distorted tripledecker and is more stable than singlet and quintet states. Cp2BzV2 stabilizes in the quintet state with a spin density of 2.4 on each vanadium atom. Hund's coupling plays a vital role in stabilizing the higher multiplets in case of titanium and vanadium clusters. In bigger clusters like Cp3Bz2M4, Sc multidecker has one unpaired spin, Ti multidecker has five unpaired spins, and V multidecker has seven unpaired spins in total. Spin polarized electronic transport is found for all states of vanadium tripledecker and one state of the titanium tripledecker when connected to a gold two probe junction. Moderate to high-spin filter efficiencies are calculated for these states. Cp2BzSc2 shows spin-independent electronic transport for all electronic states when introduced in the gold two probe junction. Current versus voltage curves are reported for selected clusters in the two probe setup.
    Keywords: density functional theory; electronic structure; Green's function methods; organic compounds; scandium compounds; spin polarised transport; titanium compounds; vanadium compounds; ATK; Application; spintronics
    Area: molecular electronics; spin
    BibTeX: 
    @article{Das2011,
  author = {Das, Bidisa and De Raychaudhury, Molly},
  title = {Electronic structure and transport properties of early transition metal tripledeckers},
  journal = {Journal of Chemical Physics},
  publisher = {AIP},
  year = {2011},
  volume = {134},
  number = {1},
  pages = {014709--10},
  url = {http://link.aip.org/link/?JCP/134/014709/1},
  doi = {http://dx.doi.org/10.1063/1.3524535}
}
    Irina Petreska, Ljupco Pejov & Ljupco Kocarev Exploring the possibilities to control the molecular switching properties and dynamics: A field-switchable rotor-stator molecular system

    [Abstract] [BibTeX]

    		 2011 J. Chem. Phys.
    Vol. 134(1), 014708-12     		 URL 
    Abstract: A bistable, dipolar stator-rotor molecular system-candidate for molecular electronics is investigated. We demonstrate that it is possible to control the intramolecular torsional states and dynamics in this system by applying an appropriate additional electric field (instead of biasing one), achieving fine tuning and modulation of the relevant properties. The electric field effects on the quantities responsible for torsional dynamics (potential energy surface, potential barrier height, quantum and classical transition probabilities, correlation time, HOMO-LUMO gap) are studied from first principles. Our results indicate that it is possible to artificially stabilize the metastable conformational state of the studied molecule. The importance of this is evident, as the current-voltage characteristics of the metastable state are clearly distinguishable from the current-voltage characteristics of the two stable states. We report for the first time exact calculations related to the possibilities to control the thermally induced stochastic switching, and reduce the noise in a practical application. Thus, we believe that the molecule studied in this paper could operate as a field-switchable molecular device under real conditions.
    Keywords: ab initio calculations; electric field effects; librational states; metastable states; molecular electronics; potential energy surfaces; radiative lifetimes; rotors; stators; ATK; Application
    Area: molecular electronics
    BibTeX: 
    @article{Petreska2011,
  author = {Petreska, Irina and Pejov, Ljupco and Kocarev, Ljupco},
  title = {Exploring the possibilities to control the molecular switching properties and dynamics: A field-switchable rotor-stator molecular system},
  journal = {J. Chem. Phys.},
  publisher = {AIP},
  year = {2011},
  volume = {134},
  number = {1},
  pages = {014708--12},
  url = {http://link.aip.org/link/?JCP/134/014708/1}
}
    Jing Yu, Guiling Zhang, Yan Shang, Hui Zhang, Luqing Yang, Tao Zeng, Bo Liu & Zesheng Li Rare earth element doping effect on the bonding and the transport property of delta-MoN

    [Abstract] [BibTeX]

    		 2011 Theoretical Chemistry Accounts: Theory, Computation, and Modeling (Theoretica Chimica Acta)
    Vol. 128(3), 285-293     		 DOI  
    Abstract: Combining non-equilibrium Green's function technique with density functional theory, the rare earth element doping effect on the bonding and the transport property of delta-MoN were theoretically investigated. The Mo-N bond lengths become more uneven after dopings. Some Mo-N bonds were heavily lengthened by the La- and Gd-dopings, resulting in obvious damages of their bonding. Evident covalent-like La-N and Gd-N bonds were formed in La-MoN and Gd-MoN, respectively, while the Yb atom underwent an ionic-like interaction with its neighboring N atoms in Yb-MoN. A clear drop of the conductivity was found after La- and Gd-dopings. On the contrary, the conductivity was improved upon the Yb-doping. This case was rationalized from the carrier density and the scattering of the carriers. The backscattering effect was evident at the impurities. The La- and Gd-dopings could not effectively increase the carrier density near the Fermi level, while the Yb atom could offer f-carriers to transfer from the valence band to the conduction band.
    Keywords: ATK; Application; doping; interface; Rare earth element; Doping effect; d-MoN; Theoretical study
    Area: interfaces
    BibTeX: 
    @article{Yu2011b,
  author = {Yu, Jing and Zhang, Guiling and Shang, Yan and Zhang, Hui and Yang, Luqing and Zeng, Tao and Liu, Bo and Li, Zesheng},
  title = {Rare earth element doping effect on the bonding and the transport property of delta-MoN},
  journal = {Theoretical Chemistry Accounts: Theory, Computation, and Modeling (Theoretica Chimica Acta)},
  publisher = {Springer Berlin / Heidelberg},
  year = {2011},
  volume = {128},
  number = {3},
  pages = {285--293},
  doi = {http://dx.doi.org/10.1007/s00214-010-0845-0}
}
    Hongmei Liu, Nan Wang, Peng Li, Xing Yin, Cui Yu, Nengyue Gao & Jianwei Zhao Theoretical investigation into molecular diodes integrated in series using the non-equilibrium Green's function method

    [Abstract] [BibTeX]

    		 2011 Phys. Chem. Chem. Phys.
    Vol. 13(4), 1301-1306     		 DOI  
    Abstract: We have conducted a theoretical study on the electronic transport behaviour of two molecular diodes connected in series. The single diode is composed of o-nitrotoluene and o-aminotoluene connecting via a [sigma]-bridge, and the tandem diode is two single diodes connecting via a [small pi]-bridge. It was found that the rectification ratio was greatly improved due to the electronic coupling in the tandem diode. The rectification ratio of the tandem molecular diode can be 20 times higher than that of the single diode, which is quite different from a traditional diode. In addition, we also found that the high rectification ratio correlates with the intramolecular coupling of the tandem system. When long conjugated wires are employed in two single diodes, the rectification ratio is reduced.
    Keywords: ATK; Application; molecular electronics; diode; rectification;
    Area: molecular electronics
    BibTeX: 
    @article{Liu2011,
  author = {Liu, Hongmei and Wang, Nan and Li, Peng and Yin, Xing and Yu, Cui and Gao, Nengyue and Zhao, Jianwei},
  title = {Theoretical investigation into molecular diodes integrated in series using the non-equilibrium Green's function method},
  journal = {Phys. Chem. Chem. Phys.},
  publisher = {The Royal Society of Chemistry},
  year = {2011},
  volume = {13},
  number = {4},
  pages = {1301--1306},
  doi = {http://dx.doi.org/10.1039/C0CP00118J}
}
    Xia Cheng, Chuan-Lu Yang, Xiao-Fei Tong, Mei-Shan Wang & Xiao-Guang Ma Na effect on the electronic transport properties of C-20 H-20 molecule

    [Abstract] [BibTeX]

    		 2011 Acta Physica Sinica
    Vol. 60(1), 017302     		 URL 
    Abstract: Using first-principles density functional theory and non-equilibrium Green's function method, we investigate the electronic transport properties of Na@ C20H20 molecule. The calculational results show that the I-V curve exhibits good linear characteristic in the range of bias [-1, 1] V, and shows obvious negative differential resistance (NDR) characteristics. The equilibrium conductance of Na@ C20H20 molecule is 0. 0101 G(0). Comparing the results with those of Li @ C(20)H(20)molecule, we find that doping Na can improve both the electronic transport capacity and the chemistry stability of C20H20 molecule, which makes it more suitable as candidate of molecular device.
    Keywords: ATK; Application; fullerenes; negative differential resistance; NDR; doping
    Area: fullerenes
    BibTeX: 
    @article{Cheng2011,
  author = {Cheng, Xia and Yang, Chuan-Lu and Tong, Xiao-Fei and Wang, Mei-Shan and Ma, Xiao-Guang},
  title = {Na effect on the electronic transport properties of C-20 H-20 molecule},
  journal = {Acta Physica Sinica},
  year = {2011},
  volume = {60},
  number = {1},
  pages = {017302},
  url = {http://wulixb.iphy.ac.cn/cn/ch/common/view_abstract.aspx?flag=1&file_no=W20110191}
}
    R. Chowdhury, S. Adhikari, P. Rees, S.P. Wilks & F. Scarpa Graphene-based biosensor using transport properties

    [Abstract] [BibTeX]

    		 2011 Phys. Rev. B
    Vol. 83(4), 045401     		 DOI  
    Abstract: The potential of graphene nanoribbons (GNR's) as molecular-scale sensors is investigated by calculating the electronic properties of the ribbon and the organic molecule ensemble. The organic molecule is assumed to be absorbed at the edge of a zigzag GNR. These nanostructures are described using a single-band tight-binding Hamiltonian. Their transport spectrum and density of states are calculated using the nonequilibrium Green's function formalism. The results show a significant suppression of the density of states (DOS), with a distinct response for the molecule. This may be promising for the prospect of GNR-based single-molecule sensors that might depend on the DOS (e.g., devices that respond to changes in either conductance or electroluminescence). Further, we have investigated the effect of doping on the transport properties of the system. The substitutional boron and nitrogen atoms are located at the center and edge of GNR's. These dopant elements have significant influence on the transport characteristics of the system, particularly doping at the GNR edge.
    Keywords: ATK; Application; graphene nanoribbon; sensor; adsorption;
    Area: graphene
    BibTeX: 
    @article{Chowdhury2011,
  author = {Chowdhury, R. and Adhikari, S. and Rees, P. and Wilks, S. P. and Scarpa, F.},
  title = {Graphene-based biosensor using transport properties},
  journal = {Phys. Rev. B},
  publisher = {American Physical Society},
  year = {2011},
  volume = {83},
  number = {4},
  pages = {045401},
  doi = {http://dx.doi.org/10.1103/PhysRevB.83.045401}
}
    Shang-Chieh Hsieh, Shih-Min Wang & Feng-Yin Li A theoretical investigation of the effect of adsorbed NO2 molecules on electronic transport in semiconducting single-walled carbon nanotubes

    [Abstract] [BibTeX]

    		 2011 Carbon
    Vol. 49(3), 955-965     		 DOI  
    Abstract: We investigated the variation of electronic transport in a semiconducting single-walled carbon nanotube (SWCNT) due to NO2 molecules adsorbed on different locations of the SWCNT surface through a theoretical means. Our results indicate that the electronic conductance of a semiconducting SWCNT strongly depends on the distance between the electrode and the NO2 adsorption site. In some cases, the conductance variation can reach ten fold. Negative differential resistance behavior is identified in the current-voltage characteristics when a NO2 molecule is adsorbed on the surface of a semiconducting SWCNT. These phenomena originate from the interaction between the electrode and the NO2 due to the finite length of the SWCNT. A NO2 sensing mechanism of an SWCNT-based chemical sensor at low NO2 concentration was proposed. Several examples of this SWCNT-based sensor adsorbed with two NO2 molecules were used to demonstrate the complicated conductivity variation when the multiple NO2 adsorptions take place in an SWCNT-based NO2 gas sensor.
    Keywords: ATK; Application; nanotube; adsorption; sensor;
    Area: nanotubes
    BibTeX: 
    @article{Hsieh2011,
  author = {Hsieh, Shang-Chieh and Wang, Shih-Min and Li, Feng-Yin},
  title = {A theoretical investigation of the effect of adsorbed NO2 molecules on electronic transport in semiconducting single-walled carbon nanotubes},
  journal = {Carbon},
  year = {2011},
  volume = {49},
  number = {3},
  pages = {955--965},
  doi = {http://dx.doi.org/10.1016/j.carbon.2010.09.062}
}
    Sang Uck Lee, Hiroshi Mizuseki & Yoshiyuki Kawazoe Electron transport characteristics of one-dimensional heterojunctions with multi-nitrogen-doped capped carbon nanotubes

    [Abstract] [BibTeX]

    		 2010 Nanoscale
    Vol. 2(12), 2758-2764     		 DOI  
    Abstract: We present a systematic analysis of electron transport characteristics for one-dimensional heterojunctions with two multi-nitrogen-doped (multi-N-doped) capped carbon nanotubes (CNTs) facing one another at different numbers of nitrogen atoms and conformations. Our results show that the modification of the molecular orbitals by the nitrogen dopants generates conducting channels in the designed heterojunctions inducing multi-switching behavior with sequential negative differential resistance (NDR). The NDR behavior significantly depends on the doping site and conformation of doped nitrogen atoms. Furthermore, we provide a clear interpretation for the NDR behavior by a rigid shift model of the HOMO- and LUMO-filtered energy levels in the left and right electrodes under the applied biases. We believe that our results will give an insight into the design and implementation of various electronic logic functions based on CNTs for applications in the field of nanoelectronics.
    Keywords: ATK; Application; carbon nanotube; doping; NDR; negative differential resistance; switching;
    Area: nanotubes
    BibTeX: 
    @article{Lee2010,
  author = {Lee, Sang Uck and Mizuseki, Hiroshi and Kawazoe, Yoshiyuki},
  title = {Electron transport characteristics of one-dimensional heterojunctions with multi-nitrogen-doped capped carbon nanotubes},
  journal = {Nanoscale},
  publisher = {The Royal Society of Chemistry},
  year = {2010},
  volume = {2},
  number = {12},
  pages = {2758--2764},
  doi = {http://dx.doi.org/10.1039/C0NR00411A}
}
    R.N. Wang, X.H. Zheng, Z.X. Dai, H. Hao, L.L. Song & Z. Zeng Anchoring group effects in molecular devices: An ab initio study on the electronic transport of a carbon-dimer

    [Abstract] [BibTeX]

    		 2011 Physics Letters A
    Vol. 375(3), 657-660     		 DOI  
    Abstract: The conductance of a molecular device is sensitive to the contact geometry between the molecules and the probing electrodes. Taking a carbon-dimer C2 as an example and connecting it to the electrodes by different linking atoms H, Cu and S, we investigate the anchoring group effect in molecular devices by the first-principles approaches. The results exhibit that, depending on the anchoring groups and the subsequent different metal-molecule chemical bonds, the current varies over more than two orders of magnitude under the same bias. This emphasizes the great importance of the anchoring groups in molecular devices.
    Keywords: Anchoring group effects, Electronic transport, First-principles, ATK, Application
    Area: molecular electronics
    BibTeX: 
    @article{Wang2011a,
  author = {Wang, R.N. and Zheng, X.H. and Dai, Z.X. and Hao, H. and Song, L.L. and Zeng, Z.},
  title = {Anchoring group effects in molecular devices: An ab initio study on the electronic transport of a carbon-dimer},
  journal = {Physics Letters A},
  year = {2011},
  volume = {375},
  number = {3},
  pages = {657--660},
  doi = {http://dx.doi.org/10.1016/j.physleta.2010.11.031}
}
    Cui Yu, Hongmei Liu, Wenbin Ni, Nengyue Gao, Jianwei Zhao & Haoli Zhang Theoretical study of the source-drain current and gate leakage current to understand the graphene field-effect transistors

    [Abstract] [BibTeX]

    		 2011 Phys. Chem. Chem. Phys.
    Vol. 13(8), 3461-3467     		 DOI  
    Abstract: We designed acene molecules attached to two semi-infinite metallic electrodes to explore the source-drain current of graphene and the gate leakage current of the gate dielectric material in the field-effect transistors (FETs) device using the first-principles density functional theory combined with the non-equilibrium Green's function formalism. In the acene-based molecular junctions, we modify the connection position of the thiol group at one side, forming different electron transport routes. The electron transport routes besides the shortest one are defined as the cross channels. The simulation results indicate that electron transport through the cross channels is as efficient as that through the shortest one, since the conductance is weakly dependent on the distance. Thus, it is possible to connect the graphene with multiple leads, leading the graphene as a channel utilized in the graphene-based FETs in the mesoscopic system. When the conjugation of the cross channel is blocked, the junction conductance decreases dramatically. The differential conductance of the BA-1 is nearly 7 (54.57 [small mu ]S) times as large as that of the BA-4 (7.35 [small mu ]S) at zero bias. Therefore, the blocked graphene can be employed as the gate dielectric material in the top-gated graphene FET device, since the leakage current is small. The graphene-based field-effect transistors fabricated with a single layer of graphene as the channel and the blocked graphene as the gate dielectric material represent one way to overcome the problem of miniaturization which faces the new generation of transistors.
    Keywords: ATK; Application; graphene; field-effect transistor
    Area: graphene
    BibTeX: 
    @article{Yu2011,
  author = {Yu, Cui and Liu, Hongmei and Ni, Wenbin and Gao, Nengyue and Zhao, Jianwei and Zhang, Haoli},
  title = {Theoretical study of the source-drain current and gate leakage current to understand the graphene field-effect transistors},
  journal = {Phys. Chem. Chem. Phys.},
  publisher = {The Royal Society of Chemistry},
  year = {2011},
  volume = {13},
  number = {8},
  pages = {3461--3467},
  doi = {http://dx.doi.org/10.1039/C0CP01026J}
}
    P. Zhao, D.S. Liu, P.J. Wang, Z. Zhang, C.F. Fang & G.M. Ji First-principles study of the electronic transport properties of the anthraquinone-based molecular switch

    [Abstract] [BibTeX]

    		 2011 Physica B: Condensed Matter
    Vol. 406(4), 895-898     		 DOI  
    Abstract: By applying non-equilibrium Green's function (NEGF) formalism combined with first-principles density functional theory (DFT), we have investigated the electronic transport properties of the anthraquinone-based molecular switch. The molecule that comprises the switch can be converted between the hydroquinone (HQ) and anthraquinone (AQ) forms via redox reactions. The transmission spectra of these two forms are remarkably distinctive. Our results show that the current through the HQ form is significantly larger than that through the AQ form, which suggests that this system has attractive potential application in future molecular switch technology.
    Keywords: molecular switch; anthraquinone, non-equilibrium Green's function; electronic transport; ATK; Application
    Area: molecular electronics
    BibTeX: 
    @article{Zhao2011,
  author = {Zhao, P. and Liu, D.S. and Wang, P.J. and Zhang, Z. and Fang, C.F. and Ji, G.M.},
  title = {First-principles study of the electronic transport properties of the anthraquinone-based molecular switch},
  journal = {Physica B: Condensed Matter},
  year = {2011},
  volume = {406},
  number = {4},
  pages = {895--898},
  doi = {http://dx.doi.org/10.1016/j.physb.2010.12.023}
}
    Nikolai Lebedev, Igor Griva, Gary S. Kedziora, Anders Blom & Joel M. Schnur The Effect of Water on Electron Transfer through Conductive Oligo(phenylene vinylene) Quinones

    [Abstract] [BibTeX]

    		 2010 The Journal of Physical Chemistry C
    Vol. 114(51), 22710-22717     		 DOI  
    Abstract: Electron transfer (ET) through oxidized (QOPV) and reduced-protonated (HQOPV) forms of oligo(phenylene vinylene) quinone placed between two gold electrodes in the absence and presence of external water molecules is calculated using density functional theory with a nonequilibrium Green's function method. The results show that the presence of hydrogen atoms as an internal component (in reduced-protonated form of the molecule) screens the stimulating effect of oxygen on QOPV conductivity and eliminates the efficiency of the molecule conductance at low bias voltages. The formation of a complex with water restores the HQOPV conductivity at low biases and opens several additional strong conductivity channels below the Fermi level, substantially improving the efficiency of ET between QOPV and the electrode, especially at longer distances between the molecule and the metal. This effect of water can be utilized in the construction of novel highly efficient electrochemically gated electronic devices. It also opens a possibility for the fine regulation of direction of ET in "soft" molecular electronic devices with flexible organization and in biological systems.
    Keywords: ATK; Application; molecular electronics; OPV; water; gate
    Area: molecular electronics
    BibTeX: 
    @article{Lebedev2010a,
  author = {Lebedev, Nikolai and Griva, Igor and Kedziora, Gary S. and Blom, Anders and Schnur, Joel M.},
  title = {The Effect of Water on Electron Transfer through Conductive Oligo(phenylene vinylene) Quinones},
  journal = {The Journal of Physical Chemistry C},
  publisher = {American Chemical Society},
  year = {2010},
  volume = {114},
  number = {51},
  pages = {22710--22717},
  doi = {http://dx.doi.org/10.1021/jp108868z}
}
    Jakob Kryger Sørensen, Jeppe Fock, Anders Holmen Pedersen, Asger B. Petersen, Karsten Jennum, Klaus Bechgaard, Kristine Kilså, Victor Geskin, Jérôme Cornil, Thomas Bjørnholm & Mogens Brøndsted Nielsen Fulleropyrrolidine End-Capped Molecular Wires for Molecular Electronics - Synthesis, Spectroscopic, Electrochemical, and Theoretical Characterization

    [Abstract] [BibTeX]

    		 2011 The Journal of Organic Chemistry
    Vol. 76(1), 245-263     		 DOI  
    Abstract: In continuation of previous studies showing promising metal-molecule contact properties a variety of C60 end-capped "molecular wires" for molecular electronics were prepared by variants of the Prato 1,3-dipolar cycloaddition reaction. Either benzene or fluorene was chosen as the central wire, and synthetic protocols for derivatives terminated with one or two fullero[c]pyrrolidine "electrode anchoring" groups were developed. An aryl-substituted aziridine could in some cases be employed directly as the azomethine ylide precursor for the Prato reaction without the need of having an electron-withdrawing ester group present. The effect of extending the pi-system of the central wire from 1,4-phenylenediamine to 2,7-fluorenediamine was investigated by absorption, fluorescence, and electrochemical methods. The central wire and the C60 end-groups were found not to electronically communicate in the ground state. However, the fluorescence of C60 was quenched by charge transfer from the wire to C60. Quantum chemical calculations predict and explain the collapse of coherent electronic transmission through one of the fulleropyrrolidine-terminated molecular wires.
    Keywords: ATK; Application; molecular electronics; fullerene; molecular wires; experimental comparison
    Area: fullerenes
    BibTeX: 
    @article{Sorensen2011,
  author = {Sørensen, Jakob Kryger and Fock, Jeppe and Pedersen, Anders Holmen and Petersen, Asger B. and Jennum, Karsten and Bechgaard, Klaus and Kilså, Kristine and Geskin, Victor and Cornil, Jérôme and Bjørnholm, Thomas and Nielsen, Mogens Brøndsted},
  title = {Fulleropyrrolidine End-Capped Molecular Wires for Molecular Electronics - Synthesis, Spectroscopic, Electrochemical, and Theoretical Characterization},
  journal = {The Journal of Organic Chemistry},
  publisher = {American Chemical Society},
  year = {2011},
  volume = {76},
  number = {1},
  pages = {245--263},
  doi = {http://dx.doi.org/10.1021/jo102066x}
}
    GuiLing Zhang, HongLiang Yuan, Hui Zhang, Yan Shang, Miao Sun, Bo Liu & ZeSheng Li Theoretical studies of the transport property of oligosilane

    [Abstract] [BibTeX]

    		 2010 SCIENCE CHINA Chemistry
    Vol. 53(12), 2571-2580     		 DOI  
    Abstract: The transport mechanisms of four sigma-conjugated systems were comparatively studied by combining ATK and Gaussian 03 calculations. It was found that the charge-doped oligosilane behaved in a different way from the boron doped and phosphorus doped oligosilanes in terms of the transmission property. The charge-doped oligosilane showed almost no conductivity owing to the damage of the electron transfer path by charge-doping. By contrast, the boron doped and phosphorus doped oligosilanes were demonstrated to be good semiconductors and NDR behavior was observed for them. This is a reasonable result after the analysis of the transmission spectra, MPSH states, energy gap, conjugation effect, and scattering effect.
    Keywords: Chemistry; ATK; Application; oligosilane; theoretical study; transport property; oligosilane; doping; NDR;
    Area: molecular electronics
    BibTeX: 
    @article{Zhang2010b,
  author = {Zhang, GuiLing and Yuan, HongLiang and Zhang, Hui and Shang, Yan and Sun, Miao and Liu, Bo and Li, ZeSheng},
  title = {Theoretical studies of the transport property of oligosilane},
  journal = {SCIENCE CHINA Chemistry},
  publisher = {Science China Press, co-published with Springer},
  year = {2010},
  volume = {53},
  number = {12},
  pages = {2571--2580},
  doi = {http://dx.doi.org/10.1007/s11426-010-4147-0}
}
    Kurt Stokbro First-Principles Modeling of Molecular Single-Electron Transistors

    [Abstract] [BibTeX]

    		 2010 The Journal of Physical Chemistry C
    Vol. 114(48), 20461-20465     		 DOI URL 
    Abstract: We present a first-principles method for calculating the charging energy of a molecular single-electron transistor operating in the coulumb blockade regime. The properties of the molecule are modeled using density-functional theory, the environment is described by a continuum model, and the interaction between the molecule and the environment is treated self-consistently through the Poisson equation. The model is used to calculate the charge stability diagrams of a benzene and C60 molecular single-electron transistor.
    Keywords: ATK; Application; Background; single-electron transistors; Coulomb blockade; first-principles; charge stability diagram;
    Area: molecular electronics
    BibTeX: 
    @article{Stokbro2010a,
  author = {Stokbro, Kurt},
  title = {First-Principles Modeling of Molecular Single-Electron Transistors},
  journal = {The Journal of Physical Chemistry C},
  publisher = {American Chemical Society},
  year = {2010},
  volume = {114},
  number = {48},
  pages = {20461--20465},
  url = {http://pubs.acs.org/doi/abs/10.1021/jp104811r},
  doi = {http://dx.doi.org/10.1021/jp104811r}
}
    Feng Gao, Jianmin Qu & Matthew Yao Effects of local structural defects on the electron transport in a carbon nanotube between Cu electrodes

    [Abstract] [BibTeX]

    		 2010 Appl. Phys. Lett.
    Vol. 97(24), 242112-3     		 DOI URL 
    Abstract: Using the first-principles approach with the Landauer formalism, we studied the effects of monovacancy and Stone-Wales defects on the electrical conductance of carbon nanotube (CNT) itself and its junction with copper electrodes. We found that the Stone-Wales defect has almost negligible impact on the electrical performance of the CNT(5,5) and its junction with copper at the Fermi level, while the monovacancy can reduce the electrical conductance of the CNT(5,5) significantly and that of the Cu/CNT(5,5)/Cu junction by more than 30%.
    Keywords: ab initio calculations; carbon nanotubes; copper; density functional theory; electrical conductivity; electrodes; Fermi level; Green's function methods; metal-semiconductor-metal structures; vacancies (crystal); ATK; Application
    Area: nanotubes
    BibTeX: 
    @article{Gao2010a,
  author = {Gao, Feng and Qu, Jianmin and Yao, Matthew},
  title = {Effects of local structural defects on the electron transport in a carbon nanotube between Cu electrodes},
  journal = {Appl. Phys. Lett.},
  publisher = {AIP},
  year = {2010},
  volume = {97},
  number = {24},
  pages = {242112--3},
  url = {http://link.aip.org/link/?APL/97/242112/1},
  doi = {http://dx.doi.org/10.1063/1.3527918}
}
    Yi-Peng An, Chuan-Lu Yang, Mei-Shan Wang, Xiao-Guang Ma & De-Hua Wang Ab initio investigations of the charge transport properties of endohedral M@C20 (M = Na and K) metallofullerenes

    [Abstract] [BibTeX]

    		 2010 Chinese Physics B
    Vol. 19(11), 113402     		 DOI URL 
    Abstract: Using density functional theory and quantum transport calculations based on nonequilibum Green's function formalism, we investigate the charge transport properties of endohedral M@C20 (M = Na and K) metallofullerenes. Our results show that the conductance of C 20 fullerene can be obviously improved by insertion of alkali atom at its centre. Both linear and nonlinear sections are found on the I-V curves of the Au-M@C20 -Au two-probe systems. The novel negative differential resistance behaviour is also observed in Na@C20 molecule but not in K@C20 .
    Keywords: negative differential resistance; conductance; first-principles; molecules; cluster; metal; metallofullerenes; electronic transport; density functional theory; nonequilibum Green's function; ATK; Application
    Area: fullerenes
    BibTeX: 
    @article{An2010b,
  author = {Yi-Peng An and Chuan-Lu Yang and Mei-Shan Wang and Xiao-Guang Ma and De-Hua Wang},
  title = {Ab initio investigations of the charge transport properties of endohedral M@C20 (M = Na and K) metallofullerenes},
  journal = {Chinese Physics B},
  year = {2010},
  volume = {19},
  number = {11},
  pages = {113402},
  url = {http://stacks.iop.org/1674-1056/19/i=11/a=113402},
  doi = {http://dx.doi.org/10.1088/1674-1056/19/11/113402}
}
    Y.D. Guo, X.H. Yan & Y. Xiao Spin-polarized current generated by carbon chain and finite nanotube

    [Abstract] [BibTeX]

    		 2010 J. Appl. Phys.
    Vol. 108(10), 104309-7     		 DOI URL 
    Abstract: Inspired by recent progress of experimental fabrication of carbon structure [ Borrnert et al., Phys. Rev. B 81, 085439 (2010) ], we proposed a scheme to generate spin-polarized current based on an all-carbon system consisting of carbon nanotube and chain. The transmission spectra are calculated based on density functional theory combined with nonequilibrium Green's function method. It is found that the spin-polarized current can be achieved in the proposed system by partial contact between nanotube and chain, without using the dopants, ferromagnetic electrodes, and external electric field. Moreover, our results show that the device containing carbon nanotubes with large length and diameter can produce the current with 100% spin polarization, which is essential for spintronic devices. Physical mechanisms and the comparison with the results of graphene are also discussed.
    Keywords: carbon nanotubes; density functional theory; Green's function methods; spin polarised transport, ATK; Application
    Area: nanotubes
    BibTeX: 
    @article{Guo2010,
  author = {Guo, Y. D. and Yan, X. H. and Xiao, Y.},
  title = {Spin-polarized current generated by carbon chain and finite nanotube},
  journal = {J. Appl. Phys.},
  publisher = {AIP},
  year = {2010},
  volume = {108},
  number = {10},
  pages = {104309--7},
  url = {http://link.aip.org/link/?JAP/108/104309/1},
  doi = {http://dx.doi.org/10.1063/1.3510537}
}
    Zhiyong Wang, Keke Zhao, Hong Li, Zheng Liu, Zujin Shi, Jing Lu, Kazu Suenaga, Soon-Kil Joung, Toshiya Okazaki, Zhaoxia Jin, Zhennan Gu, Zhengxiang Gao & Sumio Iijima Ultra-narrow WS2 nanoribbons encapsulated in carbon nanotubes

    [Abstract] [BibTeX]

    		 2011 J. Mater. Chem.
    Vol. 21(1), 171-180     		 DOI  
    Abstract: Layered tungsten disulfide nanostructures are of both fundamental and technological interest. The widths of currently synthesized WS2 ribbons are in the microscale. By using single-walled carbon nanotubes and double-walled carbon nanotubes as templates, we fabricate WS2 nanoribbons with smooth zigzag edges and uniform widths down to 1-3 nm and layer numbers down to 1-3, dependent on the nanotube diameter. Although bulk WS2 is a nonmagnetic semiconductor, the ultra-narrow free-standing zigzag-edged WS2 nanoribbons turn out to be magnetic or nonmagnetic metals depending on the edge passivation way according to our first-principles calculations, whereas the ultra-narrow armchair-edged WS2 nanoribbons remain nonmagnetic semiconductors with a narrow gap.
    Keywords: ATK; Application; nanotube; tungsten disulfide; nanoribbon; magnetic materials;
    Area: nanotubes
    BibTeX: 
    @article{Wang2011,
  author = {Wang, Zhiyong and Zhao, Keke and Li, Hong and Liu, Zheng and Shi, Zujin and Lu, Jing and Suenaga, Kazu and Joung, Soon-Kil and Okazaki, Toshiya and Jin, Zhaoxia and Gu, Zhennan and Gao, Zhengxiang and Iijima, Sumio},
  title = {Ultra-narrow WS2 nanoribbons encapsulated in carbon nanotubes},
  journal = {J. Mater. Chem.},
  publisher = {The Royal Society of Chemistry},
  year = {2011},
  volume = {21},
  number = {1},
  pages = {171--180},
  doi = {http://dx.doi.org/10.1039/C0JM02821E}
}
    L. Zhu, K.L. Yao & Z.L. Liu Magnetic and electronic switching properties of photochromic diarylethene with two nitronyl nitroxides

    [Abstract] [BibTeX]

    		 2010 Appl. Phys. Lett.
    Vol. 97(20), 202101-3     		 DOI URL 
    Abstract: Magnetic and electronic switching properties of single photochromic diarylethene with two nitronyl nitroxides sandwiched between two gold surfaces for closed and open configurations were investigated theoretically. Apart from the negative magnetoresistance effect in closed configuration, the negative differential resistance behavior in parallel state is also attained, which are potential for electronic applications. In addition, when using Br and H to substitute F atoms in the peripheral of cyclopentene, the on-off ratios are much smaller than that of the F-ligand one.
    Keywords: magnetic switching; magnetoresistance; molecular magnetism; negative resistance; organic compounds; photochromism; spin polarised transport; ATK; Application
    Area: molecular electronics; spin
    BibTeX: 
    @article{Zhu2010a,
  author = {Zhu, L. and Yao, K. L. and Liu, Z. L.},
  title = {Magnetic and electronic switching properties of photochromic diarylethene with two nitronyl nitroxides},
  journal = {Appl. Phys. Lett.},
  publisher = {AIP},
  year = {2010},
  volume = {97},
  number = {20},
  pages = {202101--3},
  url = {http://link.aip.org/link/?APL/97/202101/1},
  doi = {http://dx.doi.org/10.1063/1.3515420}
}
    Arijit Sen & Chao-Cheng Kaun Effect of Electrode Orientations on Charge Transport in Alkanedithiol Single-Molecule Junctions

    [Abstract] [BibTeX]

    		 2010 ACS Nano
    Vol. 4(11), 6404-6408     		 DOI  
    Abstract: Using first-principles calculations based on the density functional theory and the nonequilibrium Green's functions approach, we study the charge transport in Au-alkanedithiol-Au single-molecule junctions with different electrode orientations and molecular lengths. We attribute the recently measured high-/low-conductance in these heterostructures to two distinct electrode orientations, [100] and [111], which can control the electrode-molecule coupling as well as the tunneling strength by way of diverse band structures. Our detailed analysis on the transmission spectra suggests that even a single alkanedithiol junction can serve as a double quantum-dot system to yield tunable quantum interference.
    Keywords: ATK; Application; molecular electronics; gold nanowires; electronic transport; double quantum dot; tunable quantum interference; first-principles
    Area: molecular electronics
    BibTeX: 
    @article{Sen2010a,
  author = {Sen, Arijit and Kaun, Chao-Cheng},
  title = {Effect of Electrode Orientations on Charge Transport in Alkanedithiol Single-Molecule Junctions},
  journal = {ACS Nano},
  publisher = {American Chemical Society},
  year = {2010},
  volume = {4},
  number = {11},
  pages = {6404--6408},
  doi = {http://dx.doi.org/10.1021/nn101840a}
}
    Jun He, Ke-Qiu Chen, Zhi-Qiang Fan, Li-Ming Tang & W.P. Hu Transition from insulator to metal induced by hybridized connection of graphene and boron nitride nanoribbons

    [Abstract] [BibTeX]

    		 2010 Appl. Phys. Lett.
    Vol. 97(19), 193305-3     		 DOI URL 
    Abstract: A hybridized structure constructed by zigzag boron nitride nanoribbon and zigzag graphene nanoribbon is proposed, and their band structures and electronic transport properties are calculated by applying first-principles calculations. The results show that the band gap of the hybridized structure can be tuned and transitions from insulator to metal can be realized by changing the unit number of zigzag graphene nanoribbon. The currents with different spin polarization display different behavior.
    Keywords: ab initio calculations; boron compounds; electron spin polarisation; energy gap; graphene; III-V semiconductors; metal-insulator transition; nanostructured materials; wide band gap semiconductors; ATK; Application
    Area: graphene
    BibTeX: 
    @article{He2010,
  author = {He, Jun and Chen, Ke-Qiu and Fan, Zhi-Qiang and Tang, Li-Ming and Hu, W. P.},
  title = {Transition from insulator to metal induced by hybridized connection of graphene and boron nitride nanoribbons},
  journal = {Appl. Phys. Lett.},
  publisher = {AIP},
  year = {2010},
  volume = {97},
  number = {19},
  pages = {193305--3},
  url = {http://link.aip.org/link/?APL/97/193305/1},
  doi = {http://dx.doi.org/10.1063/1.3515921}
}
    L.H. Wang, Y. Guo, C.F. Tian, X.P. Song & B.J. Ding Torsion angle dependence of the rectifying performance in molecular device with asymmetrical anchoring groups

    [Abstract] [BibTeX]

    		 2010 Physics Letters A
    Vol. 374(48), 4876-4879     		 DOI URL 
    Abstract: Using first-principles density functional theory and nonequilibrium Green's function formalism, we investigate the effect of torsion angle on the rectifying characteristics of 4'-thiolate-biphenyl-4-dithiocarboxylate sandwiched between two Au(111) electrodes. The results show that the torsion angle has an evident influence on rectifying performance of such devices. By increasing the dihedral angle between two phenyl rings, namely changing the magnitude of the intermolecular coupling effect, a different rectifying behavior can be observed in these systems. Our findings highlight that the rectifying characteristics are intimately related to dihedral angles and can provide fundamental guidelines for the design of functional molecular devices.
    Keywords: Density functional theory; Nonequilibrium Green's function; Asymmetrical anchoring group; Rectifying performance; ATK; Application; molecular electronics
    Area: molecular electronics
    BibTeX: 
    @article{Wang2010c,
  author = {Wang, L.H. and Guo, Y. and Tian, C.F. and Song, X.P. and Ding, B.J.},
  title = {Torsion angle dependence of the rectifying performance in molecular device with asymmetrical anchoring groups},
  journal = {Physics Letters A},
  year = {2010},
  volume = {374},
  number = {48},
  pages = {4876--4879},
  url = {http://www.sciencedirect.com/science/article/B6TVM-515SRB8-1/2/f1365675c598962f90eeab1074861815},
  doi = {http://dx.doi.org/10.1016/j.physleta.2010.09.068}
}
    Sabyasachi Sen & Swapan Chakrabarti Ferromagnetically Coupled Cobalt-Benzene-Cobalt: The Smallest Molecular Spin Filter with Unprecedented Spin Injection Coefficient

    [Abstract] [BibTeX]

    		 2010 Journal of the American Chemical Society
    Vol. 132(43), 15334-15339     		 DOI  
    Abstract: Here, we predict that the ferromagnetically coupled cobalt-benzene-cobalt system will act as the smallest molecular spin filter with unprecedented spin injection coefficient. To validate our in-silico observation, we have performed state-of-the-art nonequilibrium Green's function calculations and analyzed the density of states of cobalt at the relativistic and nonrelativistic level of theory. Remarkably, we found that unpaired 3d electrons of cobalt are not participating in the spin transport process like other transition metal containing multidecker complexes. Instead, an admixture of the outer-sphere 4s and 4p orbitals of cobalt along with the 2p orbital of carbon of the benzene moiety is contributing to the singly occupied highest molecular orbital in the majority spin channel that creates a path for coherent spin transport leading to the extremely high spin injection coefficient of the system. The absence of the 3d electrons of cobalt in the spin transport process has been carefully examined, and it was found that the nodal structure of the 3d orbital of cobalt is not at all suitable for bonding in the cobalt-benzene-cobalt system. The whole study indicates that the underlying mechanism of the spin filter action in cobalt-benzene-cobalt is completely distinctive from the other known materials.
    Keywords: ATK; Application; spin; magnetic materials; molecular spin filter;
    Area: spin
    BibTeX: 
    @article{Sen2010,
  author = {Sen, Sabyasachi and Chakrabarti, Swapan},
  title = {Ferromagnetically Coupled Cobalt-Benzene-Cobalt: The Smallest Molecular Spin Filter with Unprecedented Spin Injection Coefficient},
  journal = {Journal of the American Chemical Society},
  publisher = {American Chemical Society},
  year = {2010},
  volume = {132},
  number = {43},
  pages = {15334--15339},
  doi = {http://dx.doi.org/10.1021/ja106705m}
}
    Changfeng Fang, Peng Zhao, Bin Cui, Lili Wang, Desheng Liu & Shijie Xie Current rectification in single molecule C59N: Effect of molecular polarity induced dipole moment

    [Abstract] [BibTeX]

    		 2010 Physics Letters A
    Vol. 374(43), 4465-4470     		 DOI URL 
    Abstract: By applying non-equilibrium Green's function formalism combined with density functional theory, we have investigated the electronic transport properties of nitrogen doped fullerene absorbed on the self-assembled alkanethiol monolayer. The molecular dipole moment, which in microscopy leads to the molecule-electrode coupling changing asymmetrically is responsible for the observed molecular rectification.
    Keywords: Electronic transport; Rectification; Dipole moment; Non-equilibrium Green's function; fullerene; molecular electronics; ATK; Application
    Area: fullerenes
    BibTeX: 
    @article{Fang2010,
  author = {Fang, Changfeng and Zhao, Peng and Cui, Bin and Wang, Lili and Liu, Desheng and Xie, Shijie},
  title = {Current rectification in single molecule C59N: Effect of molecular polarity induced dipole moment},
  journal = {Physics Letters A},
  year = {2010},
  volume = {374},
  number = {43},
  pages = {4465--4470},
  url = {http://www.sciencedirect.com/science/article/B6TVM-50YF6FN-4/2/55eb8c3104f6ad7e7913f5dab1e87f89},
  doi = {http://dx.doi.org/10.1016/j.physleta.2010.09.004}
}
    H. Liu, X. Chen & Y. Bu Redox-induced configuration conversion for thioacetamide dimer can function as a molecular switch

    [Abstract] [BibTeX]

    		 2010 J. Comput. Chem.
    Vol. 31(14), 2533-2539     		 DOI  
    Abstract: Abstract 10.1002/jcc.21512.abs The electronic switching properties of thioacetamide dimer (TAD) were investigated using the nonequilibrium Green's function method combined with density functional theory for design of a novel molecular switch. The H-bonded TAD can be converted upon hole-trapping to a three-electron (3e)-bonded configuration with a S∴S linkage which could provide a more favorable channel for charge transfer than the before. The redox-induced configuration conversion between the H-bonded and the 3e-bonded TADs could govern the charge migration through the molecular junction with a considerable difference in conduction currents. The calculated I–V characteristic curves of two configurations exhibit a switching behavior with an On-Off ratio in a range of about 4.3–7.6 within the applied voltages. Clearly, this hypothetical scheme provides a potential way to explore the novel conformation-dependent molecular switch. © 2010 Wiley Periodicals, Inc. J Comput Chem 2010
    Keywords: thioacetamide dimer; molecular switch; charge conduction; H-bond and three-electron bond; DFT calculations; ATK; Application
    Area: molecular electronics
    BibTeX: 
    @article{Liu2010d,
  author = {Liu, H. and Chen, X. and Bu, Y.},
  title = {Redox-induced configuration conversion for thioacetamide dimer can function as a molecular switch},
  journal = {J. Comput. Chem.},
  publisher = {Wiley Subscription Services, Inc., A Wiley Company},
  year = {2010},
  volume = {31},
  number = {14},
  pages = {2533--2539},
  doi = {http://dx.doi.org/10.1002/jcc.21512}
}
    Shuji Abe Modeling of molecular switches and sensors

    [BibTeX]

    		 2010 CICSJ Bulletin
    Vol. 27(5), 124     		 URL 
    Keywords: ATK; molecular electronics; sensor; Application
    Area: molecular electronics
    BibTeX: 
    @article{Abe2010,
  author = {Shuji Abe},
  title = {Modeling of molecular switches and sensors},
  journal = {CICSJ Bulletin},
  year = {2010},
  volume = {27},
  number = {5},
  pages = {124},
  url = {http://www.jstage.jst.go.jp/article/cicsj/27/5/27_124/_article/-char/ja}
}
    J. Karamdel, M. Damghanian, F. Anian, F. Razaghian, C.F. Dee & B. Yeop Majlis Dependence of Band Structure and Carrier Concentration of Metallic (13,13) and Semiconducting (13,0) Single Wall Carbon Nanotube on Temperature

    [Abstract] [BibTeX]

    		 2010 Sains Malaysiana
    Vol. 39(4), 615-620     		 URL 
    Abstract: The electronic band structure, density of states (DOS) and carrier concentration of a (13,13) metallic and a (13,0) semiconducting Single Wall Carbon Nanotube (SWCNT) have been estimated and simulated by using the Fermi-Dirac distribution function. The energy dispersion E(k) relation for metallic SWCNT near the minimum energy is linear and the Fermi level was independent of temperature (T). On the other hand for semiconducting SWCNT the E(k) relation is parabolic. The normalized Fermi-Energy (EF-EC) in the nondegenerate regime is a weak (logarithmic) function of carrier concentration and varies linearly with T. In the degenerate condition, the Fermi level was independent of T and was a strong function of carrier concentration.
    Keywords: nanotubes; ATK; Application
    Area: nanotubes
    BibTeX: 
    @article{Karamdel2010,
  author = {J. Karamdel and M. Damghanian and F. Anian and F. Razaghian and C.F. Dee and B. Yeop Majlis},
  title = {Dependence of Band Structure and Carrier Concentration of Metallic (13,13) and Semiconducting (13,0) Single Wall Carbon Nanotube on Temperature},
  journal = {Sains Malaysiana},
  year = {2010},
  volume = {39},
  number = {4},
  pages = {615-620},
  url = {http://pkukmweb.ukm.my/~jsm/english_journals/vol39num4_2010/vol39num4_2010pg615-620.html}
}
    Hong Li, Xin Yan, Guangfu Luo, Rui Qin, Qihang Liu, Lili Yu, Chengyong Xu, Jiaxin Zheng, Jing Zhou, Jing Lu, Zhengxiang Gao, Shigeru Nagase & Wai Ning Mei Functionalized Metallic Single-Walled Carbon Nanotubes as a High-Performance Single-Molecule Organic Field Effect Transistor: An ab Initio Study

    [Abstract] [BibTeX]

    		 2010 The Journal of Physical Chemistry C
    Vol. 114(37), 15816-15822     		 DOI  
    Abstract: We propose a novel single-molecule organic field effect transistor (FET) fabricated via covalent functionalization of an individual metallic single-walled carbon nanotube (SWCNT). The transfer characteristic of this FET is calculated by using ab initio quantum transport calculations. Because of the significantly reduced screening effect of the quasi-one-dimensional electrode and seamless connection between the electrode and scattering region, the optimized device shows an excellent overall performance over the experimental single-molecule organic field effect transistors. This renders functionalized metallic SWCNTs a promising candidate for a high-performance single-molecule organic field effect transistor.
    Keywords: ATK; Application; nanotube; FET; transistors;
    Area: nanotubes
    BibTeX: 
    @article{Li2010d,
  author = {Li, Hong and Yan, Xin and Luo, Guangfu and Qin, Rui and Liu, Qihang and Yu, Lili and Xu, Chengyong and Zheng, Jiaxin and Zhou, Jing and Lu, Jing and Gao, Zhengxiang and Nagase, Shigeru and Mei, Wai Ning},
  title = {Functionalized Metallic Single-Walled Carbon Nanotubes as a High-Performance Single-Molecule Organic Field Effect Transistor: An ab Initio Study},
  journal = {The Journal of Physical Chemistry C},
  publisher = {American Chemical Society},
  year = {2010},
  volume = {114},
  number = {37},
  pages = {15816--15822},
  doi = {http://dx.doi.org/10.1021/jp106535q}
}
    Y.W. Li, Z.L. Yin, J.H. Yao, X.S. Deng & C.L. Yang Effect of CO adsorption on the electron transport behavior of single Fe-porphyrin molecular wire

    [Abstract] [BibTeX]

    		 2010 Physica E: Low-dimensional Systems and Nanostructures
    Vol. 43(1), 382-386     		 DOI URL 
    Abstract: The effect of CO adsorption on the electron transport behavior of single Fe-porphyrin molecular wire with sulfur end groups bonded to two gold (1 1 1) electrodes is investigated using nonequilibrium Green's function formalism combined with first-principles density functional theory. The current-voltage characteristics of the single Fe-porphyrin molecular wires with and without CO adsorption are calculated. The results demonstrate that Fe-porphyrin molecular wire shows a negative differential resistance (NDR) at 2.0 V. The molecular current through Fe-porphyrin is significantly reduced after CO adsorption. Such a significant difference indicates the potential application of Fe-porphyrin as a molecular sensor and/or a molecular switch. The molecular projected self-consistent Hamiltonian (MPSH) states and transmission coefficients of the single Fe-porphyrin molecular wires with and without CO adsorption are analyzed. It is found that the changes of the MPSH states of the single Fe-porphyrin molecular wires with and without CO adsorption lead to the switching behavior. Furthermore, the transmission coefficients of the single Fe-porphyrin molecular wires with and without CO adsorption under various external voltages are also investigated. The results show that the transmissions through the highest occupied MPSH and the lowest unoccupied MPSH states of the single Fe-porphyrin molecular wire are suppressed significantly at this external voltage of 2.0 V, which causes the NDR.
    Keywords: ATK; Application: molecular wire; negative differential resistance; molecular sensor;
    Area: molecular electronics
    BibTeX: 
    @article{Li2010e,
  author = {Li, Y.W. and Yin, Z.L. and Yao, J.H. and Deng, X.S. and Yang, C.L.},
  title = {Effect of CO adsorption on the electron transport behavior of single Fe-porphyrin molecular wire},
  journal = {Physica E: Low-dimensional Systems and Nanostructures},
  year = {2010},
  volume = {43},
  number = {1},
  pages = {382-386},
  url = {http://www.sciencedirect.com/science/article/B6VMT-50VKMHD-1/2/424045b7fd660f8ded6615f3b87eb191},
  doi = {http://dx.doi.org/10.1016/j.physe.2010.08.018}
}
    Ling-Na Chen, Song-Shan Ma, Fang-Ping Ouyang, Xiao-Zan Wu, Jin Xiao & Hui Xu Negative differential resistance behaviour in N-doped crossed graphene nanoribbons

    [Abstract] [BibTeX]

    		 2010 Chinese Physics B
    Vol. 19(9), 097301     		 DOI URL 
    Abstract: By using first-principles calculations and nonequilibrium Green's function technique, we study elastic transport properties of crossed graphene nanoribbons. The results show that the electronic transport properties of molecular junctions can be modulated by doped atoms. Negative differential resistance (NDR) behaviour can be observed in a certain bias region, when crossed graphene nanoribbons are doped with nitrogen atoms at the shoulder, but it cannot be observed for pristine crossed graphene nanoribbons at low biases. A mechanism for the negative differential resistance behaviour is suggested.
    Keywords: ATK; Application; graphene; doping; nanoribbon
    Area: graphene
    BibTeX: 
    @article{Ling-Na2010,
  author = {Chen, Ling-Na and Ma, Song-Shan and Ouyang, Fang-Ping and Wu, Xiao-Zan and Xiao, Jin and Xu, Hui},
  title = {Negative differential resistance behaviour in N-doped crossed graphene nanoribbons},
  journal = {Chinese Physics B},
  year = {2010},
  volume = {19},
  number = {9},
  pages = {097301},
  url = {http://stacks.iop.org/1674-1056/19/i=9/a=097301},
  doi = {http://dx.doi.org/10.1088/1674-1056/19/9/097301}
}
    Ebrahim Nadimi, Philipp Plänitz, Rolf Öttking, Karsten Wieczorek & Christian Radehaus First Principle Calculation of the Leakage Current Through SiO_2 and SiO_xN_y Gate Dielectrics in MOSFETs

    [Abstract] [BibTeX]

    		 2010 IEEE Transactions on Electron Devices
    Vol. 57(3), 690-695     		 DOI  
    Abstract: A combination of density functional theory and nonequilibrium Green's function formalism has been applied to the atomic scale calculation of the leakage current through SiO2 and SiOxNy dielectrics of MOSFETs. Samples with different dielectric thicknesses and nitrogen concentrations have been taken into account in order to study the dependence of the leakage current on these two parameters. It has been shown that the incorporation of nitrogen atoms into SiO2 increases the density of gap states, which leads to barrier lowering for both electrons and holes. The calculated leakage currents through different SiO2 polymorphs (e.g., b-cristobalite, a-quartz, and b-quartz) show thickness dependences, which are in very good agreement with measured values for amorphous SiO2. The dependence of the leakage current on the concentration of nitrogen atom in oxynitride gate dielectrics has also been calculated and shown to be in good agreement with the values extracted from measured data.
    Keywords: interface; gate dielectrics; ATK; Application; MOSFET; density functional theory; dielectric materials; leakage currents; silicon compounds; SiO2; atomic scale calculation; barrier lowering; density functional theory; dielectric thicknesses; first principle calculation; gap states; nitrogen concentrations; nonequilibrium Green's function formalism; oxynitride gate dielectrics; polymorphs; Density functional theory (DFT)
    Area: interfaces
    BibTeX: 
    @article{Nadimi2010,
  author = {Ebrahim Nadimi and Philipp Plänitz and Rolf Öttking and Karsten Wieczorek and Christian Radehaus},
  title = {First Principle Calculation of the Leakage Current Through SiO_2 and SiO_xN_y Gate Dielectrics in MOSFETs},
  journal = {IEEE Transactions on Electron Devices},
  year = {2010},
  volume = {57},
  number = {3},
  pages = {690-695},
  doi = {http://dx.doi.org/10.1109/TED.2009.2038646}
}
    E. Nadimi, P. Plänitz, R. Öttking, M. Schreiber & C. Radehaus Single and Multiple Oxygen Vacancies in Ultrathin SiO2 Gate Dielectric and Their Influence on the Leakage Current: An Ab Initio Investigation

    [Abstract] [BibTeX]

    		 2010 IEEE Electron Device Letters
    Vol. 31(8), 881-883     		 DOI  
    Abstract: A first-principles method has been applied to the investigation of oxygen vacancies in ultrathin SiO2 gate dielectric and their influence on the gate leakage current. From the energy point of view, the most favorable site for a single vacancy has been determined to be at the Si/SiO2 interface. The formation energies of two neutral vacancies show, in general, an attractive interaction between two defects. Our results also indicate a correlation between the leakage current and the position of vacancies. As the number of vacancies increases in the oxide layer, the leakage current rises almost exponentially. A chain of five vacancies results in an increase of the leakage current by more than three orders of magnitude, which could be considered as gate-dielectric breakdown.
    Keywords: ATK; Application; dielectric materials; leakage currents; silicon compounds; SiO2; ab initio investigation; gate leakage current; gate-dielectric breakdown; multiple oxygen vacancies; ultrathin gate dielectrics; Density functional theory (DFT); MOSFET; dielectric breakdown; leakage current; nonequilibrium Green's function (NEGF); oxygen vacancy; reliability
    Area: interfaces
    BibTeX: 
    @article{Nadimi2010a,
  author = {E. Nadimi and P. Plänitz and R. Öttking and M. Schreiber and C. Radehaus},
  title = {Single and Multiple Oxygen Vacancies in Ultrathin SiO2 Gate Dielectric and Their Influence on the Leakage Current: An Ab Initio Investigation},
  journal = {IEEE Electron Device Letters},
  year = {2010},
  volume = {31},
  number = {8},
  pages = {881-883},
  doi = {http://dx.doi.org/10.1109/LED.2010.2051013}
}
    Yun Ren, Ke-Qiu Chen, Jun He, Li-Ming Tang, Anlian Pan, B.S. Zou & Yan Zhang Mechanically and electronically controlled molecular switch behavior in a compound molecular device

    [Abstract] [BibTeX]

    		 2010 Appl. Phys. Lett.
    Vol. 97(10), 103506-3     		 DOI URL 
    Abstract: A compound molecular device constructed by carbon nanotube, organic molecule, and metal electrode is proposed, and their electronic transport properties are calculated by using nonequilibrium Green's functions method in combination with the density-functional theory. The results show that mechanically controlled molecular switch, and electrically induced molecular switch behavior based on negative differential resistance can be observed in such molecular devices. The mechanism for the switch behavior is suggested.
    Keywords: carbon nanotubes; density functional theory; Green's function methods; spin polarised transport; ATK; Application
    Area: nanotubes
    BibTeX: 
    @article{Ren2010b,
  author = {Ren, Yun and Chen, Ke-Qiu and He, Jun and Tang, Li-Ming and Pan, Anlian and Zou, B. S. and Zhang, Yan},
  title = {Mechanically and electronically controlled molecular switch behavior in a compound molecular device},
  journal = {Appl. Phys. Lett.},
  publisher = {AIP},
  year = {2010},
  volume = {97},
  number = {10},
  pages = {103506--3},
  url = {http://link.aip.org/link/?APL/97/103506/1},
  doi = {http://dx.doi.org/10.1063/1.3488822}
}
    Anurag Srivastava, Neha Tyagi, U.S. Sharma & R.K. Singh Pressure induced phase transformation and electronic properties of AlAs

    [Abstract] [BibTeX]

    		 2011 Materials Chemistry and Physics
    Vol. 125(1-2), 66-71     		 DOI URL 
    Abstract: We have performed the first-principle study to analyze the structural and electronic properties of aluminum arsenide under the application of pressure. The computations have been carried out using the ground state total energy calculation approach of the system. The first-principle approach has been used to compute the stability of various phases of AlAs, like original zinc blende (B3), intermediate NiAs (B8), NaCl (B1) and CsCl (B2) type as a function of pressure. The study observes a B3-B8, B3-B1 and B3-B2 transitions at 6.99 GPa, 8.18 GPa and 73.43 GPa. The computed phase transition pressures, lattice parameters, bulk modulus, and energy gaps are in good agreement with their experimental as well as theoretical counterparts. Band structure and density of states analysis have also been performed and results have been discussed in detail.
    Keywords: Phase transition; High pressure; Electronic properties; AlAs; ATK; Application
    Area: interfaces
    BibTeX: 
    @article{Srivastava2010,
  author = {Srivastava, Anurag and Tyagi, Neha and Sharma, U.S. and Singh, R.K.},
  title = {Pressure induced phase transformation and electronic properties of AlAs},
  journal = {Materials Chemistry and Physics},
  year = {2011},
  volume = {125},
  number = {1-2},
  pages = {66-71},
  url = {http://www.sciencedirect.com/science/article/B6TX4-511K9WG-3/2/fc5363d1ca56a307a324a2d0c189025d},
  doi = {http://dx.doi.org/10.1016/j.matchemphys.2010.08.072}
}
    Wei Su, Ruixin Dong, Xunling Yan, Haijun Wang & Hao Liu Current Distance Response for Rapid DNA Sequencing

    [Abstract] [BibTeX]

    		 2010 Journal of Computational and Theoretical Nanoscience
    Vol. 7, 1885-1888     		 DOI  
    Abstract: DNA bases can be identified statistically in nanopore translocation events, but the distinct single-molecule signals for sequencing are not yet available. Here, based on state-of-the-art density functional theory together with the non-equilibrium Green's Function method, we propose a new approach that relies on functionalized nanopore-embedded electrodes to distinguish nucleic acid bases in the DNA sequencing process. Each base is identified by a characteristic current distance response when a single-stranded DNA passes through functionalized electrodes in nanopore, and there is a clearly difference between cytosine (C) and thymine (T) bases with a guanine-functionalized electrodes.
    Keywords: ATK; Application; DNA; molecular electronics;
    Area: molecular electronics
    BibTeX: 
    @article{Su2010,
  author = {Su, Wei and Dong, Ruixin and Yan, Xunling and Wang, Haijun and Liu, Hao},
  title = {Current Distance Response for Rapid DNA Sequencing},
  journal = {Journal of Computational and Theoretical Nanoscience},
  year = {2010},
  volume = {7},
  pages = {1885--1888},
  doi = {http://dx.doi.org/10.1166/jctn.2010.1554}
}
    L.H. Wang, Y. Guo, C.F. Tian, X.P. Song & B.J. Ding Negative differential resistance and rectifying behaviors in atomic molecular device with different anchoring groups

    [Abstract] [BibTeX]

    		 2010 Physica E: Low-dimensional Systems and Nanostructures
    Vol. 43(1), 524-528     		 DOI URL 
    Abstract: The electronic transport properties of molecular wires made of carbon atomic chains (triynes) capped with benzene are investigated using nonequilibrium Green's function in combination with density functional theory. The results show that the anchoring group plays a crucial role in determining the overall conductivity of the molecular junction. Negative differential resistance can be observed when the molecular wire contacts Au electrodes through a dithiocarboxylate linker on both sides, while the rectifying performance is observed when the molecular wire contacts Au electrodes through a thiol linker on one side and with a dithiocarboxylate anchoring group on the other. The mechanisms are suggested for these behaviors.
    Keywords: molecular electronics; ATK; Application; carbon atomic chains; NDR; negative differential resistance
    Area: molecular electronics
    BibTeX: 
    @article{Wang2010b,
  author = {Wang, L.H. and Guo, Y. and Tian, C.F. and Song, X.P. and Ding, B.J.},
  title = {Negative differential resistance and rectifying behaviors in atomic molecular device with different anchoring groups},
  journal = {Physica E: Low-dimensional Systems and Nanostructures},
  year = {2010},
  volume = {43},
  number = {1},
  pages = {524-528},
  url = {http://www.sciencedirect.com/science/article/B6VMT-5120K93-2/2/d8faa87187f6585d62bf8ec9052a83b7},
  doi = {http://dx.doi.org/10.1016/j.physe.2010.09.007}
}
    Cai Juan Xia Xia, Han Cheng Liu, Peng Fei Cheng & Chang Feng Fang Fang Effect of Dithiocarboxylate Anchoring Group on Electronic Transport in 4,4'-Biphenyldithiol Molecular Junction

    [Abstract] [BibTeX]

    		 2010 Key Engineering Materials
    Vol. 428-429, 232-236     		 DOI  
    Abstract: Using nonequilibrium Green's function and first-principles calculations, we investigate the effects of different molecular conformations induced by torsion angle on electronic transport and their stability in 4,4'-biphenyl bis (dithiocarboxylate) molecular junction under an applied electric field. The results indicate that there are two stable conformations existed in this molecular junction as external bias increasing. An electric field can be used to "switch" one conformation to the other, and there is an abrupt change in the degree of torsion angle in this process. This change is expected to cause a conductance switching in the system. Furthermore, the transport mechanism of this conformational molecular switch is discussed in detail.
    Keywords: ATK; Application; molecular electronics; conformational molecular switch; electronic transport; first principles calculation
    Area: molecular electronics
    BibTeX: 
    @article{Xia2010b,
  author = {Xia, Cai Juan Xia and Liu, Han Cheng and Cheng, Peng Fei and Fang, Chang Feng Fang},
  title = {Effect of Dithiocarboxylate Anchoring Group on Electronic Transport in 4,4'-Biphenyldithiol Molecular Junction},
  journal = {Key Engineering Materials},
  year = {2010},
  volume = {428-429},
  pages = {232-236},
  doi = {http://dx.doi.org/10.4028/www.scientific.net/KEM.428-429.232}
}
    B. Xu & Y.P. Feng Electronic structures and transport properties of sulfurized carbon nanotubes

    [Abstract] [BibTeX]

    		 2010 Solid State Communications
    Vol. 150(41-42), 2015-2019     		 DOI URL 
    Abstract: The electronic and transport properties of side-walled sulfurized (8, 0) zigzag carbon nanotube were investigated by using density functional theory coupled with a non-equilibrium Green function approach. It is found that the adsorption of the sulfur chains largely reduces the bandgap of the semiconducting (8, 0) carbon nanotube, even changing it into a metallic one. More importantly, the transmission eigenstates around the Fermi level are contributed by not only the sulfur chains but also the complex system made of the sulfur chains and the single-walled carbon nanotube. Our results provide a method to improve the conductivity and utilization rate of the surface in the electrodes of supercapacitor which are made of the carbon nanotubes.
    Keywords: Single-walled carbon nanotube; Electronic transport; ATK; Application
    Area: nanotubes
    BibTeX: 
    @article{Xu2010,
  author = {Xu, B. and Feng, Y.P.},
  title = {Electronic structures and transport properties of sulfurized carbon nanotubes},
  journal = {Solid State Communications},
  year = {2010},
  volume = {150},
  number = {41-42},
  pages = {2015--2019},
  url = {http://www.sciencedirect.com/science/article/B6TVW-50V20G9-1/2/0cf7254c08a920006502cfc4f2911a14},
  doi = {http://dx.doi.org/10.1016/j.ssc.2010.08.015}
}
    S Yamacli & M Avci A method for the extraction of the voltage-dependent quantum capacitance of carbon nanotubes using ab initio simulations

    [Abstract] [BibTeX]

    		 2010 Physica Scripta
    Vol. 82(4), 045705     		 DOI URL 
    Abstract: In this paper, a method to obtain the quantum capacitance of carbon nanotubes (CNTs) using ab initio simulations is presented. As an example of the usage of the proposed method, the quantum capacitance of a metallic (6,6) CNT section is calculated. The quantum capacitance is extracted for various bias voltages applied to metallic CNT interconnects in the range 0 to 2.5 V, which is the operating voltage range of VLSI circuits. The obtained quantum capacitance values are found to be in good agreement with the experimental values. The average Fermi velocity of electrons dependent on the bias voltage is also obtained and plotted.
    Keywords: ATK; Application; capacitance; nanotubes; field effect transistors;
    Area: nanotubes
    BibTeX: 
    @article{Yamacli2010a,
  author = {Yamacli, S and Avci, M},
  title = {A method for the extraction of the voltage-dependent quantum capacitance of carbon nanotubes using ab initio simulations},
  journal = {Physica Scripta},
  year = {2010},
  volume = {82},
  number = {4},
  pages = {045705},
  url = {http://stacks.iop.org/1402-4896/82/i=4/a=045705},
  doi = {http://dx.doi.org/10.1088/0031-8949/82/04/045705}
}
    Zhizhou Yu, L.Z. Sun, X.L. Wei & J.X. Zhong Novel transport properties of gold-single wall carbon nanotubes composite contacts

    [Abstract] [BibTeX]

    		 2010 J. Appl. Phys.
    Vol. 108(6), 064318-5     		 DOI URL 
    Abstract: Using the density functional theory and nonequilibrium Green's function method, we report the effect of the gold-single wall carbon nanotubes (SWCNTs) composite contacts on the electronic structures and the transport properties of the device constructed by SWCNTs [SWCNT(10,0) or SWCNT(5,5)] and gold electrodes. The transmissions of the devices are greatly improved due to the strong couplings between carbon and gold atoms of the composite contacts. As for SWCNT(10,0), the gold atoms in the composite contacts behave as n-type dopant and depress the Schottky barrier between SWCNT(10,0) and the gold electrode. Moreover, the negative differential resistance characteristics occurs in the devices constructed by gold-SWCNT(10,0) composite contacts.
    Keywords: carbon nanotubes, composite materials, density functional theory, electrical contacts, electrodes, electronic structure, gold, Green's function methods, Schottky barriers, ATK, Application
    Area: nanotubes
    BibTeX: 
    @article{Yu2010a,
  author = {Yu, Zhizhou and Sun, L. Z. and Wei, X. L. and Zhong, J. X.},
  title = {Novel transport properties of gold-single wall carbon nanotubes composite contacts},
  journal = {J. Appl. Phys.},
  publisher = {AIP},
  year = {2010},
  volume = {108},
  number = {6},
  pages = {064318--5},
  url = {http://link.aip.org/link/?JAP/108/064318/1},
  doi = {http://dx.doi.org/10.1063/1.3483246}
}
    Jia Li, Zuanyi Li, Gang Zhou, Zhirong Liu, Jian Wu, Bing-Lin Gu, Jisoon Ihm & Wenhui Duan Spontaneous edge-defect formation and defect-induced conductance suppression in graphene nanoribbons

    [Abstract] [BibTeX]

    		 2010 Phys. Rev. B
    Vol. 82(11), 115410-     		 DOI  
    Abstract: We present a first-principles study of the migration and recombination of edge defects (carbon adatom and/or vacancy) and their influence on electrical conductance in zigzag graphene nanoribbons (ZGNRs). It is found that at room temperature, the adatom is quite mobile while the vacancy is almost immobile along the edge of ZGNRs. The recombination of an adatom-vacancy pair leads to a pentagon-heptagon ring defect structure having a lower energy than the perfect edge, implying that such an edge defect can be formed spontaneously. This edge defect can suppresses the conductance of ZGNRs drastically, which provides some useful hints for understanding the observed semiconducting behavior of the fabricated narrow GNRs.
    Keywords: ATK; Application; graphene; defects;
    Area: graphene
    BibTeX: 
    @article{Li2010c,
  author = {Li, Jia and Li, Zuanyi and Zhou, Gang and Liu, Zhirong and Wu, Jian and Gu, Bing-Lin and Ihm, Jisoon and Duan, Wenhui},
  title = {Spontaneous edge-defect formation and defect-induced conductance suppression in graphene nanoribbons},
  journal = {Phys. Rev. B},
  publisher = {American Physical Society},
  year = {2010},
  volume = {82},
  number = {11},
  pages = {115410--},
  doi = {http://dx.doi.org/10.1103/PhysRevB.82.115410}
}
    Xiao-Fei Li, Hao Ren, Ling-Ling Wang, Ke-Qiu Cheng, Jinlong Yang & Yi Luo Important Structural Factors Controlling the Conductance of DNA Pairs in Molecular Junctions

    [Abstract] [BibTeX]

    		 2010 The Journal of Physical Chemistry C
    Vol. 114(33), 14240-14242     		 DOI  
    Abstract: It has been demonstrated experimentally that DNA base pairs and sequences can be identified by measuring their current changes in metal junctions. We report here a first principles study on electron transport properties of DNA base pairs in gold metal junctions. It is found that the experimentally observed electrode-separation-width-dependent current changes of DNA base pairs are not due to the difference in number of hydrogen bonds involved in different base pairs as proposed in earlier experimental studies but caused by the difference in their stacking structures. It reveals that such an electronic read-out technique is not exact, but practically useful since the statistically favorable misaligned junctions do show distinct dependence on the character of the base pair.
    Keywords: ATK; Application; DNA base pairs; molecular electronics;
    Area: molecular electronics
    BibTeX: 
    @article{Li2010b,
  author = {Li, Xiao-Fei and Ren, Hao and Wang, Ling-Ling and Cheng, Ke-Qiu and Yang, Jinlong and Luo, Yi},
  title = {Important Structural Factors Controlling the Conductance of DNA Pairs in Molecular Junctions},
  journal = {The Journal of Physical Chemistry C},
  publisher = {American Chemical Society},
  year = {2010},
  volume = {114},
  number = {33},
  pages = {14240--14242},
  doi = {http://dx.doi.org/10.1021/jp100798g}
}
    W.H. Liao, B.H. Zhou, H.Y. Wang & G.H. Zhou Electronic structures for armchair-edge graphene nanoribbons under a small uniaxial strain

    [Abstract] [BibTeX]

    		 2010 The European Physical Journal B - Condensed Matter and Complex Systems
    Vol. 76(3), 463-467     		 DOI  
    Abstract: We theoretically investigate the electronic structures for armchair-edge graphene nanoribbons (AGNRs) under a small in-plane uniaxial strain along armchair (longitudinal) and zigzag (transversal) direction, respectively. We demonstrate that, by both the tight-binding calculation and first-principles study, the applying of a small asymmetrical strain results in variation of energy subband spacing, which opens a band gap for metallic AGNRs and modifies the band gaps for semiconducting AGNRs near the Fermi level. It is believed that these results are of importance in the band gap engineering and electromechanical applications of graphene-nanoribbon-based devices.
    Keywords: ATK; Application; graphene; nanoribbon; strain
    Area: graphene
    BibTeX: 
    @article{Liao2010-08-01,
  author = {Liao, W. H. and Zhou, B. H. and Wang, H. Y. and Zhou, G. H.},
  title = {Electronic structures for armchair-edge graphene nanoribbons under a small uniaxial strain},
  journal = {The European Physical Journal B - Condensed Matter and Complex Systems},
  publisher = {Springer Berlin / Heidelberg},
  year = {2010},
  volume = {76},
  number = {3},
  pages = {463--467},
  doi = {http://dx.doi.org/10.1140/epjb/e2010-00222-3}
}
    Yun Ren, Ke-Qiu Chen, Qing Wan, Anlian Pan & W.P. Hu Negative differential resistance in polymer molecular devices modulated with molecular length

    [Abstract] [BibTeX]

    		 2010 Physics Letters A
    Vol. 374(37), 3857 - 3862     		 DOI  
    Abstract: We study the electronic transport properties of polymer molecular devices by applying first-principles method. The results show that the electronic transport properties depend on molecular length. Negative differential resistance can be observed and can be modulated with molecular length.
    Keywords: Negative differential resistance; Molecular device; First-principles; ATK; Application
    Area: molecular electronics
    BibTeX: 
    @article{Ren2010a,
  author = {Yun Ren and Ke-Qiu Chen and Qing Wan and Anlian Pan and W.P. Hu},
  title = {Negative differential resistance in polymer molecular devices modulated with molecular length},
  journal = {Physics Letters A},
  year = {2010},
  volume = {374},
  number = {37},
  pages = {3857 - 3862},
  doi = {http://dx.doi.org/10.1016/j.physleta.2010.07.040}
}
    Lei Shen, Minggang Zeng, Shuo-Wang Yang, Chun Zhang, Xuefeng Wang & Yuanping Feng Electron Transport Properties of Atomic Carbon Nanowires between Graphene Electrodes

    [Abstract] [BibTeX]

    		 2010 Journal of the American Chemical Society
    Vol. 132(33), 11481-11486     		 DOI  
    Abstract: Long, stable, and free-standing linear atomic carbon wires (carbon chains) have been carved out from graphene recently [Meyer et al. Nature (London) 2008, 454, 319; Jin et al. Phys. Rev. Lett. 2009, 102, 205501]. They can be considered as extremely narrow graphene nanoribbons or extremely thin carbon nanotubes. It might even be possible to make use of high-strength and identical (without chirality) carbon wires as a transport channel or on-chip interconnects for field-effect transistors. Here we investigate electron transport properties of linear atomic carbon wire-graphene junctions by combining nonequilibrium Green's function with density functional theory. For short wires, linear ballistic transport is observed in wires consisting of odd numbers of carbon atoms but not in those consisting of even numbers of carbon atoms. For wires longer than 2.1 nm as fabricated above, however, the ballistic conductance of carbon wire-graphene junctions is independent of the structural distortion, structural imperfections, and hydrogen impurity adsorbed on the linear carbon wires, except for oxygen impurity adsorption under a low bias. As such, the epoxy groups might be the origin of experimentally observed low conductance in the carbon chain. Moreover, double-atomic carbon chains exhibit a negative differential resistance effect.
    Keywords: ATK; Application; graphene; atomic wire;
    Area: graphene
    BibTeX: 
    @article{Shen2010,
  author = {Shen, Lei and Zeng, Minggang and Yang, Shuo-Wang and Zhang, Chun and Wang, Xuefeng and Feng, Yuanping},
  title = {Electron Transport Properties of Atomic Carbon Nanowires between Graphene Electrodes},
  journal = {Journal of the American Chemical Society},
  publisher = {American Chemical Society},
  year = {2010},
  volume = {132},
  number = {33},
  pages = {11481--11486},
  doi = {http://dx.doi.org/10.1021/ja909531c}
}
    C.J. Xia, C.F. Fang, P. Zhao & H.C. Liu Effects of contact atomic structure on the electron transport of pyridine-substituted dithienylethene optical molecular switch

    [Abstract] [BibTeX]

    		 2010 The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics
    Vol. 59(3), 375-378     		 DOI  
    Abstract: By applying nonequilibrium Green's function formalism combined with first-principles density functional theory, we investigate the effects of contact atomic structure on the electron transport of pyridine-substituted dithienylethene optical molecules with open- and closed-ring forms. The motivation for this study is the variable situations that may arise in break junction experiments. Three kinds of molecule-metal interface conformations including the hollow, bridge and top sites are studied. Theoretical results show that the conductance of the closed-ring is always larger than that of open-ring for all three connecting sites. When the molecule is located at the hollow site, this will lead to negative differential resistance under applied bias, while it cannot be found in the bridge and top sites.
    Keywords: ATK; Application; optical molecular switch;
    Area: molecular electronics
    BibTeX: 
    @article{Xia2010-09-01,
  author = {Xia, C. J. and Fang, C. F. and Zhao, P. and Liu, H. C.},
  title = {Effects of contact atomic structure on the electron transport of pyridine-substituted dithienylethene optical molecular switch},
  journal = {The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics},
  publisher = {Springer Berlin / Heidelberg},
  year = {2010},
  volume = {59},
  number = {3},
  pages = {375--378},
  doi = {http://dx.doi.org/10.1140/epjd/e2010-00196-2}
}
    Serhan Yamacli & Mutlu Avci Neural network modeling of voltage-dependent resistance of metallic carbon nanotube interconnects: An ab initio study

    [Abstract] [BibTeX]

    		 2010 Expert Systems with Applications
    Vol. 37(12), 8014-8018     		 DOI  
    Abstract: In this work, development voltage-dependent resistance models of metallic carbon nanotubes for computer aided design tools is aimed. Firstly, the resistance of metallic carbon nanotube interconnects are obtained from first principles simulations and the voltage dependence of the resistance is modeled through neural networks. Self-consistent non-equilibrium Green's function formalism combined with density functional theory is used for calculating the voltage-dependent resistance of metallic carbon nanotubes. It is shown that voltage dependent resistances of carbon nanotubes obtained from ab initio simulations can be accurately modeled via neural networks which enable rapid integration of carbon nanotube interconnect models into electronic design automation tools.
    Keywords: Carbon nanotube interconnects; Nonlinear resistance; Neural network modeling; ATK; Application; nanotube
    Area: nanotubes
    BibTeX: 
    @article{Yamacli2010,
  author = {Yamacli, Serhan and Avci, Mutlu},
  title = {Neural network modeling of voltage-dependent resistance of metallic carbon nanotube interconnects: An ab initio study},
  journal = {Expert Systems with Applications},
  year = {2010},
  volume = {37},
  number = {12},
  pages = {8014--8018},
  doi = {http://dx.doi.org/10.1016/j.eswa.2010.05.089}
}
    B.H. Zhou, W.H. Liao, B.L. Zhou, K.-Q. Chen & G.H. Zhou Electronic transport for a crossed graphene nanoribbon junction with and without doping

    [Abstract] [BibTeX]

    		 2010 The European Physical Journal B - Condensed Matter and Complex Systems
    Vol. 76(3), 421-425     		 DOI  
    Abstract: The electronic transport property for a crossed junction of graphene nanoribbons with and without impurity doping is investigated numerically by a fully self-consistent non-equilibrium Green's function method combined with density functional theory. It is demonstrated that the transport property of the junction depends sensitively on both the dopant positions and the geometry of junction. Specifically, the I-V characteristics of the junction with either nitrogen- or boron-doped stems always show metallic behavior. However, the current strongly depends on the doping atomic species and sites, but slightly depends on the geometry of junction under small bias voltage. The findings here may be important in the design of graphene-based electronic devices for realizing on/off states.
    Keywords: ATK; Application; graphene; nanoribbon; doping
    Area: graphene
    BibTeX: 
    @article{Zhou2010-08-01,
  author = {Zhou, B. H. and Liao, W. H. and Zhou, B. L. and Chen, K.-Q. and Zhou, G. H.},
  title = {Electronic transport for a crossed graphene nanoribbon junction with and without doping},
  journal = {The European Physical Journal B - Condensed Matter and Complex Systems},
  publisher = {Springer Berlin / Heidelberg},
  year = {2010},
  volume = {76},
  number = {3},
  pages = {421--425},
  doi = {http://dx.doi.org/10.1140/epjb/e2010-00181-7}
}
    Kurt Stokbro, Dan Erik Petersen, Søren Smidstrup, Anders Blom, Mads Ipsen & Kristen Kaasbjerg Semiempirical model for nanoscale device simulations

    [Abstract] [BibTeX]

    		 2010 Phys. Rev. B
    Vol. 82(7), 075420     		 DOI URL 
    Abstract: We present a semiempirical model for calculating electron transport in atomic-scale devices. The model is an extension of the extended Hückel method with a self-consistent Hartree potential that models the effect of an external bias and corresponding charge rearrangements in the device. It is also possible to include the effect of external gate potentials and continuum dielectric regions in the device. The model is used to study the electron transport through an organic molecule between gold surfaces, and it is demonstrated that the results are in closer agreement with experiments than ab initio approaches provide. In another example, we study the transition from tunneling to thermionic emission in a transistor structure based on graphene nanoribbons.
    Keywords: ATK; Application; graphene; Background
    Area: graphene
    BibTeX: 
    @article{Stokbro2010,
  author = {Stokbro, Kurt and Petersen, Dan Erik and Smidstrup, Søren and Blom, Anders and Ipsen, Mads and Kaasbjerg, Kristen},
  title = {Semiempirical model for nanoscale device simulations},
  journal = {Phys. Rev. B},
  publisher = {American Physical Society},
  year = {2010},
  volume = {82},
  number = {7},
  pages = {075420},
  url = {http://link.aps.org/doi/10.1103/PhysRevB.82.075420},
  doi = {http://dx.doi.org/10.1103/PhysRevB.82.075420}
}
    B. Feldman, S. Park, M. Haverty, S. Shankar & S.T. Dunham Simulation of grain boundary effects on electronic transport in metals, and detailed causes of scattering

    [Abstract] [BibTeX]

    		 2010 phys. stat. sol. (b)
    Vol. 247(7), 1791-1796     		 DOI  
    Abstract: We present first-principles simulations of single grain boundary reflectivity of electrons in noble metals, Cu and Ag. We examine twin and non-twin grain boundaries using non-equilibrium Green's function and first principles methods. We also investigate the determinants of reflectivity in grain boundaries by modeling atomic vacancies, disorder, and orientation and find that both the change in grain orientation and disorder in the boundary itself contribute significantly to reflectivity. We find that grain boundary reflectivity may vary widely depending on the grain boundary structure, consistent with published experimental results. Finally, we examine the reflectivity from multiple grain boundaries and find that grain boundary reflectivity may depend on neighboring grain boundaries. This study raises some potential limitations in the independent grain boundary assumptions of the Mayadas-Shatzkes (MS) model.
    Keywords: electronic conduction; first principles; grain boundaries; metals; scattering; ATK, Application
    Area: interfaces
    BibTeX: 
    @article{Feldman2010,
  author = {Feldman, B. and Park, S. and Haverty, M. and Shankar, S. and Dunham, S. T.},
  title = {Simulation of grain boundary effects on electronic transport in metals, and detailed causes of scattering},
  journal = {phys. stat. sol. (b)},
  publisher = {WILEY-VCH Verlag},
  year = {2010},
  volume = {247},
  number = {7},
  pages = {1791--1796},
  doi = {http://dx.doi.org/10.1002/pssb.201046133}
}
    Jing Huang, Qunxiang Li, Ke Xu, Haibin Su & Jinlong Yang Electronic, Magnetic, and Transport Properties of Fe-COT Clusters: A Theoretical Study

    [Abstract] [BibTeX]

    		 2010 The Journal of Physical Chemistry C
    Vol. 114(27), 11946-11950     		 DOI URL 
    Abstract: Using density functional theory calculations combined with nonequilibrium Green?s function method, we report the electronic, magnetic, and transport properties of iron-cyclooctatetraene (Fe-COT) sandwich clusters. Four Fen COTn+1 (n=1-4) clusters with linear sandwich structure are highly stable because of the strong Fe-COT coupling. The ground state of Fe-COT clusters is ferromagnetic, Fe atoms couple ferromagnetically to the neighboring COT rings, and the large total magnetic moments increase with the number of Fe atoms. The spin-polarized transport calculations indicate that Fe-COT clusters coupled to gold electrodes act as nearly perfect spin-filters. The revealed properties indicate that the Fe-COT clusters would be ideal materials for promising molecular spintronics.
    Keywords: ATK; Application; spintronics; cluster;
    Area: molecular electronics; spin
    BibTeX: 
    @article{Huang2010,
  author = {Huang, Jing and Li, Qunxiang and Xu, Ke and Su, Haibin and Yang, Jinlong},
  title = {Electronic, Magnetic, and Transport Properties of Fe-COT Clusters: A Theoretical Study},
  journal = {The Journal of Physical Chemistry C},
  year = {2010},
  volume = {114},
  number = {27},
  pages = {11946-11950},
  url = {http://pubs.acs.org/doi/abs/10.1021/jp101554c},
  doi = {http://dx.doi.org/10.1021/jp101554c}
}
    Hong Seok Kang Quantum Conductance of mu-Borolyl Triple-Decker Sandwich Complexes

    [Abstract] [BibTeX]

    		 2010 The Journal of Physical Chemistry C
    Vol. 114(25), 11266-11272     		 DOI URL 
    Abstract: Using a nonequilibrium Green's function method combined with density functional theory, we have calculated the quantum conductance of a recently synthesized -borolyl triple-decker sandwich complex, in which Ru and Co ions are sandwiched between three five-membered rings. The current-voltage characteristics of the complex when connected to Au (111) wire exhibit a strong nonlinear and asymmetric behavior at applied bias, in which multiple negative differential resistance (NDR) effects are observed. Our detailed analysis shows that the origin of the effect is quite diverse: this diversity can be attributed to the existence of a narrow bulk or surface electrode density of states and the alignment and misalignment of d-states of two metal ions. The substitution effect has been also investigated by replacing hydrogen atoms on the central ring with electronegative chlorine atoms.
    Keywords: ATK; Application; molecular electronics; NDR; negative differential resistance;
    Area: molecular electronics
    BibTeX: 
    @article{Kang2010,
  author = {Kang, Hong Seok},
  title = {Quantum Conductance of mu-Borolyl Triple-Decker Sandwich Complexes},
  journal = {The Journal of Physical Chemistry C},
  year = {2010},
  volume = {114},
  number = {25},
  pages = {11266-11272},
  url = {http://pubs.acs.org/doi/abs/10.1021/jp102551s},
  doi = {http://dx.doi.org/10.1021/jp102551s}
}
    Nikolai Lebedev, Igor Griva, Scott A. Trammell, Gary S. Kedziora, Leonard M. Tender & Joel Schnur On the Role of Oxygen in the Formation of Electron Transmission Channels in Oligo(Phenylene Vinylene) Quinone Molecular Conductance

    [Abstract] [BibTeX]

    		 2010 The Journal of Physical Chemistry C
    Vol. 114(28), 12341-12345     		 DOI URL 
    Abstract: Electron transmission parameters of oligo(phenylene vinylene) quinone (OPVQ) placed between two gold electrodes were calculated ab initio using density functional theory (DFT) with the nonequilibrium Green?s function method. Compared to oligo(phenylene vinylene) (OPV)3, the introduction of oxygen atoms into the phenyl ring for OPVQ leads to the appearance of a narrow transmission band at close proximity to the electrode Fermi levels. This band allows OPVQ to operate as an efficient n-type conductor with a single molecular electron transfer efficiency approaching 1 G0 (quantum conductance). The close location to the Fermi level and the narrow shape of the band lead to high and stable molecular conductivity even at a very low bias. The presence of an efficient transmission band close to the electrode Fermi level explains experimentally observed high molecular conductance of OPVQ, which will allow this molecule to be used in low band gap molecular electronic devices.
    Keywords: ATK; Application; molecular electronics;
    Area: molecular electronics
    BibTeX: 
    @article{Lebedev2010,
  author = {Lebedev, Nikolai and Griva, Igor and Trammell, Scott A. and Kedziora, Gary S. and Tender, Leonard M. and Schnur, Joel},
  title = {On the Role of Oxygen in the Formation of Electron Transmission Channels in Oligo(Phenylene Vinylene) Quinone Molecular Conductance},
  journal = {The Journal of Physical Chemistry C},
  year = {2010},
  volume = {114},
  number = {28},
  pages = {12341-12345},
  url = {http://pubs.acs.org/doi/abs/10.1021/jp1031042},
  doi = {http://dx.doi.org/10.1021/jp1031042}
}
    Xiao-Fei Li, Ke-Qiu Chen, Lingling Wang & Yi Luo Effects of Interface Roughness on Electronic Transport Properties of Nanotube-Molecule-Nanotube Junctions

    [Abstract] [BibTeX]

    		 2010 The Journal of Physical Chemistry C
    Vol. 114(28), 12335-12340     		 DOI URL 
    Abstract: We investigate electronic transport properties of molecular junctions constructed by a single conjugated molecule attached in the gap of two broken metallic single walled carbon nanotubes (CNTs). With the help of molecular dynamic simulations (MD), we have provided a realistic description for mechanical stretching processes of different carbon nanotubes and contact structures between the broken CNTs and the conjugated molecule in different junctions. Statistical analysis shows that the molecule generally prefers to be titled inside the junctions with polygonal contact, in particular the apex at the broken ends of tubes. Nonequilibrium Green's function (NEGF) calculations reveal that such realistic CNTs-molecular junctions have very different electron transport properties from junctions with ideal SWCNTs as electrodes. The statistically and energetically favorable CNTs-molecular junctions of different chiralities are found to be always metallic, but their absolute conductance is sensitive to the chirality of the tube. It is suggested that with armchair CNTs as electrodes, a better conductivity can be obtained. The calculated current-voltage characteristics of junctions with realistic contact geometries are in good agreement with experiments.
    Keywords: ATK; Application; nanotube
    Area: nanotubes
    BibTeX: 
    @article{Li2010a,
  author = {Li, Xiao-Fei and Chen, Ke-Qiu and Wang, Lingling and Luo, Yi},
  title = {Effects of Interface Roughness on Electronic Transport Properties of Nanotube-Molecule-Nanotube Junctions},
  journal = {The Journal of Physical Chemistry C},
  year = {2010},
  volume = {114},
  number = {28},
  pages = {12335-12340},
  url = {http://pubs.acs.org/doi/abs/10.1021/jp102945v},
  doi = {http://dx.doi.org/10.1021/jp102945v}
}
    Hongmei Liu, Cui Yu, Nengyue Gao & Jianwei Zhao The Diversity of Electron-Transport Behaviors of Molecular Junctions: Correlation with the Electron-Transport Pathway

    [Abstract] [BibTeX]

    		 2010 ChemPhysChem
    Vol. 11(9), 1895-1902     		 DOI  
    Abstract: We report the electron-transport behaviors of a number of molecular junctions composed of pi-conjugated molecular wires. From calculations performed by using density functional theory (DFT) combined with the non-equilibrium Green's function (NEGF) method, we found that the length-conductivity relations are diverse, depending on the particular molecular structures. The results reveal that the conductance-length dependence follows an exponential law for many conjugated molecules with a single channel, such as oligothiophene, oligopyrrole and oligophenylene. Therefore, a quantitative relation between the energy gap (Eg)infin of the molecular wire and the attenuation factor beta can be defined. However, when the molecular wires have multichannels, the decay of conductance does not follow the exponential relation. For example, the conductance of porphyrin-based oligomers and fused thiophene decays almost linearly. The diversity of electron-transport behaviors of molecular junctions is directly dominated by the electron-transport pathway.
    Keywords: ATK; Application; molecular electronics;
    Area: molecular electronics
    BibTeX: 
    @article{Liu2010b,
  author = {Liu, Hongmei and Yu, Cui and Gao, Nengyue and Zhao, Jianwei},
  title = {The Diversity of Electron-Transport Behaviors of Molecular Junctions: Correlation with the Electron-Transport Pathway},
  journal = {ChemPhysChem},
  year = {2010},
  volume = {11},
  number = {9},
  pages = {1895--1902},
  doi = {http://dx.doi.org/10.1002/cphc.201000092}
}
    Hongmei Liu, Zhong Xu, Nan Wang, Cui Yu, Nengyue Gao, Jianwei Zhao & Ning Li Theoretical investigation on the chemical sensing of metalloporphyrin-based molecular junction

    [Abstract] [BibTeX]

    		 2010 J. Chem. Phys.
    Vol. 132(24), 244702-9     		 DOI URL 
    Abstract: Following the previous study [ N. Wang et al., J. Phys. Chem. C 113, 7416 (2009) ] which focused on specific electron transport pathway in the cyclic molecules, we investigated the chemical sensing of the metalloporphyrin-based molecular junctions. Theoretical calculations have been carried out using density functional theory combined with the nonequilibrium Green's function method. The adsorbed molecules (CO, NO, and O2) show diverse effects which depend on the connecting position between the metalloporphyrin with the electrodes. For iron (II) porphyrin (FeP) and manganese (II) porphyrin (MnP) connected at the 9,11-position (P-connection), the electron only passes through the porphyrin ring and the binding of ligand has no effect on the molecular conductivity. However, for the FeP and MnP connected at the 1,5-position (D-connection), the molecular conductivity decreases dramatically after adsorptions of three diatomic molecules as a result of the electron takes the path through the metallic center. For the potential application of chemical sensing, the selectivities of the FeP and MnP are discussed as well.
    Keywords: adsorption, chemical sensors, electrical conductivity, Green's function methods, molecular electronics, organic compounds; ATK; Application
    Area: molecular electronics
    BibTeX: 
    @article{Liu2010c,
  author = {Liu, Hongmei and Xu, Zhong and Wang, Nan and Yu, Cui and Gao, Nengyue and Zhao, Jianwei and Li, Ning},
  title = {Theoretical investigation on the chemical sensing of metalloporphyrin-based molecular junction},
  journal = {J. Chem. Phys.},
  publisher = {AIP},
  year = {2010},
  volume = {132},
  number = {24},
  pages = {244702--9},
  url = {http://link.aip.org/link/?JCP/132/244702/1},
  doi = {http://dx.doi.org/10.1063/1.3456542}
}
    Xin Luo, S.P. Lin, Biao Wang & Yue Zheng Impact of applied strain on the electron transport through ferroelectric tunnel junctions

    [Abstract] [BibTeX]

    		 2010 Appl. Phys. Lett.
    Vol. 97(1), 012905-3     		 DOI URL 
    Abstract: Combining nonequilibrium Green's functions with density-functional theory, we have investigated the effect of external strain field on the tunneling electroresistance (TER) of ferroelectric material sandwiched between Pt electrodes. The results show that the strain induced para/ferroelectric phase transitions play an important role in the electronic transport properties of the junction. Sizable enhancements in the resistance are found for the strained ferroelectric junctions with a TER ratio of 9000%. Detail analyses show that the Ti-O displacements along the transport direction in ferroelectric barrier change the effective potential profile, resulting in a giant piezoelectric resistance in the ferroelectric tunnel junctions.
    Keywords: density functional theory, electrodes, ferroelectric transitions, Green's function methods, piezoelectricity, platinum; ATK; Application; spintronics
    Area: molecular electronics; spin
    BibTeX: 
    @article{Luo2010,
  author = {Luo, Xin and Lin, S. P. and Wang, Biao and Zheng, Yue},
  title = {Impact of applied strain on the electron transport through ferroelectric tunnel junctions},
  journal = {Appl. Phys. Lett.},
  publisher = {AIP},
  year = {2010},
  volume = {97},
  number = {1},
  pages = {012905--3},
  url = {http://link.aip.org/link/?APL/97/012905/1},
  doi = {http://dx.doi.org/10.1063/1.3462070}
}
    Masaaki Araidai & Masaru Tsukada Theoretical calculations of electron transport in molecular junctions: Inflection behavior in Fowler-Nordheim plot and its origin

    [Abstract] [BibTeX]

    		 2010 Phys. Rev. B
    Vol. 81(23), 235114     		 DOI URL 
    Abstract: We investigated the origin of an inflection behavior appearing in Fowler-Nordheim (F-N) plot of current-voltage characteristics for molecular junctions using two different levels of calculation methods: nonequilibrium Green's-function technique combined with the density-functional theory and tight-binding approximation. Although the inflection has so far been interpreted from the naive model that the charge transport mechanism transits from a direct to the F-N tunneling, our results indicated that the inflection does not necessarily mean the transition between the two regimes. We found from the close examination of the relation between the behavior of the F-N curve and the transmission function that the inflection takes place when the molecular level responsible for electric currents approaches to the edge of the bias window. While our interpretation for the inflection drastically differ from the conventional model, the F-N plots obtained from our calculations showed closely similar behavior as those from the recent experiments.
    Keywords: ATK; Application; molecular electronics
    Area: molecular electronics
    BibTeX: 
    @article{Araidai2010,
  author = {Araidai, Masaaki and Tsukada, Masaru},
  title = {Theoretical calculations of electron transport in molecular junctions: Inflection behavior in Fowler-Nordheim plot and its origin},
  journal = {Phys. Rev. B},
  publisher = {American Physical Society},
  year = {2010},
  volume = {81},
  number = {23},
  pages = {235114},
  url = {http://link.aps.org/doi/10.1103/PhysRevB.81.235114},
  doi = {http://dx.doi.org/10.1103/PhysRevB.81.235114}
}
    Zhi-Qiang Fan, Ke-Qiu Chen, Qing Wan & Yan Zhang Electronic transport properties in a bimolecular device modulated with different side groups

    [Abstract] [BibTeX]

    		 2010 Journal of Applied Physics
    Vol. 107(11), 113713     		 DOI URL 
    Abstract: By using nonequilibrium Green's functions in combination with the density-functional theory, we investigate the electronic transport properties in a bimolecular device, which is substituted by two amino groups or two nitro groups. The results show that the side groups can modulate the transport properties by their substituted position. The current of the system substituted by two amino groups on the same side is bigger than that on the different side. Contrarily, the current of the system substituted by two nitro groups on the same side is smaller than that on the different side. More importantly, the negative differential resistance (NDR) behavior can be observed only when the system substituted by two amino groups on the same side. The mechanisms are proposed for the effect of the side groups and NDR behavior.
    Keywords: density functional theory; electrical resistivity; Green's function methods; molecular electronics; ATK; Application
    Area: molecular electronics
    BibTeX: 
    @article{Fan2010b,
  author = {Zhi-Qiang Fan and Ke-Qiu Chen and Qing Wan and Yan Zhang},
  title = {Electronic transport properties in a bimolecular device modulated with different side groups},
  journal = {Journal of Applied Physics},
  publisher = {AIP},
  year = {2010},
  volume = {107},
  number = {11},
  pages = {113713},
  url = {http://link.aip.org/link/?JAP/107/113713/1},
  doi = {http://dx.doi.org/10.1063/1.3446294}
}
    Y. Min, K.L. Yao, H.H. Fu, Z.L. Liu & Q. Li First-principles study of strong rectification and negative differential resistance induced by charge distribution in single molecule

    [Abstract] [BibTeX]

    		 2010 The Journal of Chemical Physics
    Vol. 132(21), 214703     		 DOI URL 
    Abstract: For molecule-scale transport systems, a mechanism that the charge distribution of molecule under the various bias voltages can induce strong effect of rectification and negative differential resistance is proposed. Based on nonequilibrium Green's function combined with density functional theory, the proposal is testified by performing the first-principles calculations of transport characteristics of 2-(4'-thiolate-butyl)-6-thiol-anthrecene molecule sandwiched in two gold electrodes. The strong effect of rectification and negative differential resistance is obtained. The rectification effect is as large as 16.
    Keywords: Green's function methods; molecular electronics; rectification; ATK; Application
    Area: molecular electronics
    BibTeX: 
    @article{Min2010,
  author = {Y. Min and K. L. Yao and H. H. Fu and Z. L. Liu and Q. Li},
  title = {First-principles study of strong rectification and negative differential resistance induced by charge distribution in single molecule},
  journal = {The Journal of Chemical Physics},
  publisher = {AIP},
  year = {2010},
  volume = {132},
  number = {21},
  pages = {214703},
  url = {http://link.aip.org/link/?JCP/132/214703/1},
  doi = {http://dx.doi.org/10.1063/1.3447380}
}
    Rui Qin, Jing Lu, Lin Lai, Jing Zhou, Hong Li, Qihang Liu, Guangfu Luo, Lina Zhao, Zhengxiang Gao, Wai Ning Mei & Guangping Li Room-temperature giant magnetoresistance over one billion percent in a bare graphene nanoribbon device

    [Abstract] [BibTeX]

    		 2010 Phys. Rev. B
    Vol. 81(23), 233403     		 DOI  
    Abstract: We provide ab initio study on a spin valve device that is based on bare ferromagnetic zigzag-edged graphene nanoribbons. Giant magnetoresistance over one billion percent at room temperature is obtained, which is an ultrahigh magnetoresistance among graphene-related spin valve devices and seven orders of magnitude larger than the available experimental values. The orbital parity mismatching between the sigma and pi* bands and enhanced exchange splitting due to the dangling bond are two indispensable factors to generate this large magnetoresistance.
    Keywords: ATK; Application; spin; graphene;
    Area: graphene; spin
    BibTeX: 
    @article{Qin2010,
  author = {Qin, Rui and Lu, Jing and Lai, Lin and Zhou, Jing and Li, Hong and Liu, Qihang and Luo, Guangfu and Zhao, Lina and Gao, Zhengxiang and Mei, Wai Ning and Li, Guangping},
  title = {Room-temperature giant magnetoresistance over one billion percent in a bare graphene nanoribbon device},
  journal = {Phys. Rev. B},
  publisher = {American Physical Society},
  year = {2010},
  volume = {81},
  number = {23},
  pages = {233403},
  doi = {http://dx.doi.org/10.1103/PhysRevB.81.233403}
}
    S.P. Koiry, D.K. Aswal, B. Jousselme, C. Majumdar, S.K. Gupta, S. Palacin & J.V. Yakhmi Negative differential resistance in electrografted layer of N-(2-(4-diazoniophenyl)ethyl)-N'-hexylnaphthalene-1,8:4,5-tetracarboxydiimide tetrafluoroborate on Si

    [Abstract] [BibTeX]

    		 2010 Chemical Physics Letters
    Vol. 493(1-3), 135 - 140     		 DOI URL 
    Abstract: We demonstrate electrochemical deposition of a specially designed and synthesized [sigma]-[pi]-[sigma] molecular architecture, that is, N-(2-(4-diazoniophenyl)ethyl)-N'-hexylnaphthalene-1,8:4,5-tetracarboxydiimide tetrafluoroborate (DHTT), on H-terminated Si substrates. Electrografting of DHTT on Si at 5 and 27 °C leads to the formation of monolayer and multilayers, respectively. DHTT monolayer exhibits a pronounced negative differential resistance (NDR) in the current-voltage characteristics with peak-to-valley current ratio of ~10. Theoretical simulations studies show that the observed NDR effect is intrinsic to the DHTT molecules. NDR effect has been explained using the ab initio molecular-orbital theoretical calculations.
    Keywords: ATK; Application; molecular electronics
    Area: molecular electronics
    BibTeX: 
    @article{Koiry2010,
  author = {S.P. Koiry and D.K. Aswal and B. Jousselme and C. Majumdar and S.K. Gupta and S. Palacin and J.V. Yakhmi},
  title = {Negative differential resistance in electrografted layer of N-(2-(4-diazoniophenyl)ethyl)-N'-hexylnaphthalene-1,8:4,5-tetracarboxydiimide tetrafluoroborate on Si},
  journal = {Chemical Physics Letters},
  year = {2010},
  volume = {493},
  number = {1-3},
  pages = {135 - 140},
  url = {http://www.sciencedirect.com/science/article/B6TFN-5046MCH-2/2/536b60c73ad33d9fa7ed24a9e1ef784d},
  doi = {http://dx.doi.org/10.1016/j.cplett.2010.05.038}
}
    Vihar P. Georgiev & John E. McGrady Efficient Spin Filtering through Cobalt-Based Extended Metal Atom Chains

    [Abstract] [BibTeX]

    		 2010 Inorganic Chemistry
    Vol. 49(12), 5591-5597     		 DOI  
    Abstract: Density functional theory in conjunction with nonequilibrium Green's functions has been used to explore charge transport through the cobalt-based extended metal atom chain, Co3(dpa)4(NCS)2. The isolated molecule has a doublet ground state, and the singly occupied sigma nonbonding orbital proves to be the dominant transport channel, providing spin filtering efficiencies in excess of 90%. The metal chain differs from typical organic conductors in that the pi orbitals that form the contact with the gold electrode are orthogonal to the transport channel. As a result, the rehybridization of these pi levels by the applied electric field has only a minor impact on the current, allowing spin filtering to persist even at biases in excess of 1 V.
    Keywords: molecular electronics; ATK; Application; spin; magnetic systems; atomic chains;
    Area: molecular electronics; spin
    BibTeX: 
    @article{Georgiev2010,
  author = {Georgiev, Vihar P. and McGrady, John E.},
  title = {Efficient Spin Filtering through Cobalt-Based Extended Metal Atom Chains},
  journal = {Inorganic Chemistry},
  publisher = {American Chemical Society},
  year = {2010},
  volume = {49},
  number = {12},
  pages = {5591--5597},
  doi = {http://dx.doi.org/10.1021/ic100493t}
}
    L.H. Wang, Y. Guo, C.F. Tian, X.P. Song & B.J. Ding Effect of the indices of crystal plane of gold electrodes on the transport properties of C[sub 20] fullerene

    [Abstract] [BibTeX]

    		 2010 Journal of Applied Physics
    Vol. 107(10), 103702     		 DOI URL 
    Abstract: Using first-principles density functional theory and nonequilibrium Green's function formalism, we investigate the effect of the indices of crystal plane of electrodes on the electronic transport properties of molecular devices by taking C20 fullerene molecule as conductor component and semi-infinite Au(111)/(100) as electrodes. The results show that the transport behaviors through molecular devices are closely related to the crystallographic orientation of electrodes. Negative differential resistance (NDR) in the current-voltage curve can be observed for the Au(100) electrode case but cannot be observed for the Au(111) case. A mechanism for the NDR phenomenon is proposed.
    Keywords: ab initio calculations; crystal orientation; density functional theory; electrical resistivity; electrodes; fullerenes; gold; Green's function methods; molecular electronics; fullerene; ATK; Application
    Area: fullerenes
    BibTeX: 
    @article{Wang2010a,
  author = {L. H. Wang and Y. Guo and C. F. Tian and X. P. Song and B. J. Ding},
  title = {Effect of the indices of crystal plane of gold electrodes on the transport properties of C[sub 20] fullerene},
  journal = {Journal of Applied Physics},
  publisher = {AIP},
  year = {2010},
  volume = {107},
  number = {10},
  pages = {103702},
  url = {http://link.aip.org/link/?JAP/107/103702/1},
  doi = {http://dx.doi.org/10.1063/1.3391350}
}
    Xinqian Li, Aleksandar Staykov & Kazunari Yoshizawa Orbital Views of the Electron Transport through Polycyclic Aromatic Hydrocarbons with Different Molecular Sizes and Edge Type Structures

    [Abstract] [BibTeX]

    		 2010 The Journal of Physical Chemistry C
    Vol. 114(21), 9997-10003     		 DOI  
    Abstract: In this work electron-transport properties of pi-conjugated polycyclic aromatic hydrocarbons with different molecular sizes and edge type structures are investigated. The applicability of a derived concept for orbital control of electron transport (J. Am. Chem. Soc. 2008, 130, 9406) is tested on larger hydrocarbons in order to estimate its predictive power for different types of compounds. Favorable connections for effective electron transport in pi-conjugated systems with weak coupling between the molecules and electrodes are predicted on the basis of the orbital symmetry rule by looking at the phase and amplitude of the frontier orbitals. Qualitative predictions based on frontier orbital analysis are compared with density functional theory calculations for realistic molecular junctions with strong covalent bonds between a molecule and two gold electrodes. Obtained results are in good agreement with the orbital symmetry rule predictions, which makes the frontier orbitals' analysis a powerful tool in electron transport studies in pi-conjugated polycyclic aromatic hydrocarbons.
    Keywords: ATK; Application; molecular electronics;
    Area: molecular electronics
    BibTeX: 
    @article{Li2010,
  author = {Li, Xinqian and Staykov, Aleksandar and Yoshizawa, Kazunari},
  title = {Orbital Views of the Electron Transport through Polycyclic Aromatic Hydrocarbons with Different Molecular Sizes and Edge Type Structures},
  journal = {The Journal of Physical Chemistry C},
  publisher = {American Chemical Society},
  year = {2010},
  volume = {114},
  number = {21},
  pages = {9997--10003},
  doi = {http://dx.doi.org/10.1021/jp102280r}
}
    H. Hao, X.H. Zheng, Z.X. Dai & Z. Zeng Spin-filtering transport and switching effect of MnCu single-molecule magnet

    [Abstract] [BibTeX]

    		 2010 Applied Physics Letters
    Vol. 96(19), 192112     		 DOI URL 
    Abstract: Electron transport of a single-molecule magnet (SMM) device has been investigated using the first-principles calculations. The SMM based device is constructed by a SMM MnCu [MnCuCl(5-Br-sap)2(MeOH)] bridged between semi-infinite Au(100) electrodes with thiol groups connecting the molecule and the gold electrodes. Our results exhibit crucial features of spin filtering and Kondo resonance. The spin filtering remains robust, whereas the Kondo resonance highly depends on the contact geometry. Specifically, this Kondo resonance can be switched on or off by changing the contact distance. The mechanisms of these features are formulated in details.
    Keywords: ab initio calculations; copper compounds; Kondo effect; magnetic switching; magnetoelectronics; manganese compounds; molecular electronics; molecular magnetism; organic compounds; ATK; Application
    Area: spin; molecular electronics
    BibTeX: 
    @article{Hao2010,
  author = {H. Hao and X. H. Zheng and Z. X. Dai and Z. Zeng},
  title = {Spin-filtering transport and switching effect of MnCu single-molecule magnet},
  journal = {Applied Physics Letters},
  publisher = {AIP},
  year = {2010},
  volume = {96},
  number = {19},
  pages = {192112},
  url = {http://link.aip.org/link/?APL/96/192112/1},
  doi = {http://dx.doi.org/10.1063/1.3430063}
}
    Guiling Zhang, Yue Qin, Hui Zhang, Yan Shang, Miao Sun, Bo Liu & Zesheng Li Electronic Structure-Transport Property Relationships of Polyferrocenylene, Polyferrocenylacetylene, and Polyferrocenylsilane

    [Abstract] [BibTeX]

    		 2010 The Journal of Physical Chemistry C
    Vol. 114(20), 9469-9477     		 DOI  
    Abstract: Combining nonequilibrium Green's function technique with density functional theory, the electronic structure-transport property relationships of polyferrocenylene, polyferrocenylacetylene, and polyferrocenylsilane were comparatively studied. We have found that the bridge group between two adjacent ferrocene units plays an important role in tuning their conductivity. The conductivity follows the sequence polyferrocenylene, polyferrocenylacetylene, and polyferrocenylsilane, in agreement with the experimental observation. The sequence cannot be interpreted by different band gaps; electronic structure factors such as Fe-Fe, Fe-cyclopentadienyl, and cyclopentadienyl-bridge group interactions, which influence the conductivity, are identified.
    Keywords: ATK; Application; molecular electronics; ferrocene; iron
    Area: molecular electronics
    BibTeX: 
    @article{Zhang2010a,
  author = {Zhang, Guiling and Qin, Yue and Zhang, Hui and Shang, Yan and Sun, Miao and Liu, Bo and Li, Zesheng},
  title = {Electronic Structure-Transport Property Relationships of Polyferrocenylene, Polyferrocenylacetylene, and Polyferrocenylsilane},
  journal = {The Journal of Physical Chemistry C},
  publisher = {American Chemical Society},
  year = {2010},
  volume = {114},
  number = {20},
  pages = {9469--9477},
  doi = {http://dx.doi.org/10.1021/jp912030d}
}
    D.T. Smith, J.R. Pratt, F. Tavazza, L.E. Levine & A.M. Chaka An ultrastable platform for the study of single-atom chains

    [Abstract] [BibTeX]

    		 2010 Journal of Applied Physics
    Vol. 107(8), 084307     		 DOI URL 
    Abstract: We describe a surface probe instrument capable of sustaining single atomic bond junctions in the electronic quantum conduction regime for tens of minutes, and present results for Au junctions that can be "locked" stably in n = 1 and n = 2 quantum conduction states with electrical conductivity n*G0 (G0 = 2e^2/h) and switched in a controlled way. The instrument measures and controls the gap formed between a probe and a flat surface with better than 5 pm long-term stability in a high-vacuum chamber at 4 K using a high-sensitivity fiber-optic interferometer that forms a Fabry-Perot cavity immediately adjacent and parallel to the probe. We also report the experimental observation of stable noninteger conduction states, along with preliminary density functional theory-based calculations of one-dimensional (1D) and two-dimensional Au "bridges" that produce comparable noninteger conduction states. Finally, we report the observation of novel stochastic processes related to nonballistic electron transport through strained single atomic bond junctions. The instrument permits detailed study of electron transport in 1D systems, and the long-term picometer stability of the junction holds great promise for application to single-molecule spectroscopy.
    Keywords: ballistic transport; density functional theory; electrical conductivity; gold; nanowires; stochastic processes; ATK; Application
    Area: nanowires
    BibTeX: 
    @article{Smith2010,
  author = {D. T. Smith and J. R. Pratt and F. Tavazza and L. E. Levine and A. M. Chaka},
  title = {An ultrastable platform for the study of single-atom chains},
  journal = {Journal of Applied Physics},
  publisher = {AIP},
  year = {2010},
  volume = {107},
  number = {8},
  pages = {084307},
  url = {http://link.aip.org/link/?JAP/107/084307/1},
  doi = {http://dx.doi.org/10.1063/1.3369584}
}
    Peng Zhao, PeiJi Wang, Zhong Zhang & DeSheng Liu Capped carbon nanotube-based molecular switch

    [Abstract] [BibTeX]

    		 2010 Chinese Science Bulletin
    Vol. 55(13), 1227-1230     		 DOI  
    Abstract: Using the Landauer formalism that combines both the non-equilibrium Green's function (NEGF) and first-principles density functional theory (DFT), the electron transport characteristics of one-dimensional molecular switching device based on the capped carbon nanotubes have been investigated. The results show that the transmission can be efficiently tuned within two orders of magnitude just by changing 0.2 nm of the tube-tube separation. Moreover, the electron transport is insensitive to the topology of the facing conformations which can improve the practical stability of the chosen system as a molecular switch.
    Keywords: carbon nanotubes; molecular switch; non-equilibrium Green function; density functional theory; ATK; Application; fullerene
    Area: nanotubes
    BibTeX: 
    @article{Zhao2010e,
  author = {Zhao, Peng and Wang, PeiJi and Zhang, Zhong and Liu, DeSheng},
  title = {Capped carbon nanotube-based molecular switch},
  journal = {Chinese Science Bulletin},
  year = {2010},
  volume = {55},
  number = {13},
  pages = {1227--1230},
  doi = {http://dx.doi.org/10.1007/s11434-010-0142-2}
}
    Zhizhou Yu, L.Z. Sun, C.X. Zhang & J.X. Zhong Transport properties of corrugated graphene nanoribbons

    [Abstract] [BibTeX]

    		 2010 Applied Physics Letters
    Vol. 96(17), 173101     		 DOI URL 
    Abstract: The transport properties of the devices made by corrugated graphene nanoribbons were investigated using the density functional theory in combination with the nonequilibrium Green's function method. We find that the transport properties of the zigzag graphene nanoribbons (ZGNRs) with arched corrugation are similar to the flat one, while the transmission of the ZGNRs with step-shaped corrugation is greatly depressed. As for the armchair graphene nanoribbons (AGNRs), arched corrugation enlarges the transmission gap and the threshold voltage of the device. Moreover, the open currents of AGNRs are significantly depressed by both stepped and arched corrugation.
    Keywords: density functional theory; graphene; Green's function methods; nanostructured materials; transport processes; ATK; Application;
    Area: graphene
    BibTeX: 
    @article{Yu2010,
  author = {Zhizhou Yu and L. Z. Sun and C. X. Zhang and J. X. Zhong},
  title = {Transport properties of corrugated graphene nanoribbons},
  journal = {Applied Physics Letters},
  publisher = {AIP},
  year = {2010},
  volume = {96},
  number = {17},
  pages = {173101},
  url = {http://link.aip.org/link/?APL/96/173101/1},
  doi = {http://dx.doi.org/10.1063/1.3419821}
}
    Xiaoqing Deng, Zhenhua Zhang, Jicheng Zhou, Ming Qiu & Guiping Tang Length and end group dependence of the electronic transport properties in carbon atomic molecular wires

    [