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The best way to learn how to use VNL and ATK as effectively as possible is to look as some concrete examples.
The manuals contains some examples intended to show users how to operate specific parts of the software, but otherwise they are mainly reference documents, in particular for NanoLanguage.
In this section, we will collect tutorials that outline a more complete work flow, from the initial definition of the geometry through to the final analysis of the results. Typically, we will be focusing on a particular type of system or calculation, and we will also demonstrate how to combine scripting and the graphical user interface in VNL in a flexible and powerful way.
General guides
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Title & Abstract
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Upgrade guide
Primarily intended for experienced users of ATK 2008.10 and earlier versions, this upgrade guide contains important details about the two-probe model, and other useful information regarding ATK 10.8. It also includes two mini-tutorials for quickly getting to know the new graphical user interface.
Open tutorial (html | PDF)
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Parallel guide
Running ATK in parallel can provide a substantial performance benefit. In fact, you don't even need a cluster to take advantage of parallelism, since ATK also uses OpenMP to speed up the calculations on multicore machines! This guide will explain how to run ATK in parallel, which parts of the calculations that are parallelized, and many other useful details. It also discusses various strategies for balancing the number of nodes and cores, and even provides some example PBS scripts.
Open tutorial (html | PDF)
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Tutorials for ATK 10.8
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Title & Abstract
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Getting started
This is a general, quick introduction to basic calculations in ATK, with a focus on getting to know the graphical user interface. By performing some simple molecule calculations, using the semi-empirical edition of ATK, the user will be guided through the basic concepts of the software. The purpose of this tutorial is not on the results themselves, but on how to operate the software.
Open tutorial (html | PDF)
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Introduction to transport calculations with ATK
The most outstanding feature in ATK is its ability to compute the ballistic tunneling current in nanoscale device structures. This tutorial provides an introduction to transport calculations with ATK by considering a toy system (a hydrogen molecule embedded in an atomic chain of Li atoms), and presents basic concepts such as computing the transmission spectrum, I-V curve, and voltage drop, and also shows to optimize the geometry, etc.
Open tutorial (html)
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Transport in graphene nanoribbons
This basic tutorial serves as an introduction to many of the basic features in ATK and VNL, by studying electronic structure and transport properties of both perfect and distorted graphene nanoribbons.
Open tutorial (html | PDF)
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Electronic structure of NiO with LDA+U
One of the exciting new features in ATK 10.8 is LDA+U. By tuning the empirical Hubbard parameter U, one can obtain the correct band gap for semiconductors even with LDA or GGA (coming later). This tutorial shows how to approach this type of calculations by taking NiO as an example, and at the same time it also introduces the new density of states (DOS) functionality in ATK 10.8.
Open tutorial (html | PDF)
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Benzene single electron transistor
Insipred by K. Kaasbjerg and K. Flensberg, Nano Letters, 8, 3809 (2008), this rather advanced tutorial presents in detail how ATK can be used to investigate weakly coupled single electron transistor devices, where the transport mechanism is sequential tunneling (Coulomb blockade), rather than ballistic tunneling. Specifically, the fully self-consistent charge stability diagram is computed (picture left), using the electrostatic gate capability in ATK.
Open tutorial (html | PDF)
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Exploring graphene with ATK
This advanced tutorial goes deeper into the the Python scripting language in ATK, and shows how scripting, in combination with the functionality in the graphical user interface, can be used to set up advanced structures such as twisted graphene ribbons. The tutorial presents how users themselves can construct Custom Builders in VNL, a form of graphical plug-ins that make it easy to define and manipulate parameterized geometries.
Open tutorial (html | PDF)
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Graphene junction device - a nanoscale transistor
This extensive tutorial presents how the semi-empirical method in ATK can be used to investigate a nanoscale transistor. The structure is a graphene junction, inspired by Q. Yan et al., Nano Letters 7, 1469 (2007). We study the current as a function of the electrode bias, the gate potential, and even the (electron) temperature.
Open tutorial (html | PDF)
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Introduction to GPAW in VNL
A brief tutorial which presents how to do some simple calculations using GPAW from within VNL.
Open tutorial (html | PDF)
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Tutorials for ATK/VNL 2008.10
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Title & Abstract
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ATK Tutorial
What Everyone Should Know About ATK
Applies to ATK 2008.10. Will be updated to 10.8 soon!
The title says it all - this is a very fundamental (albeit not basic) presentation of all the important details that you should know about ATK. Part 1 is related to the geometry setup and the self-consistent calculation, while Part 2 deals with transmission analysis. The focus is naturally on two-probe systems, but important points for bulk and molecular calculations are also presented.
Download Part 1 (PDF)
Download Part 2 (PDF)
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Spin Bloch states in nanoribbons
Depending on the edge shape, graphene nanoribbons have metallic or semiconducting characteristics, but spin also plays an important role. We will use the capabilities of ATK to study the spin-dependent band structure of a zigzag ribbon. By plotting conduction and valence band Bloch states, we will see how the two spin-components are localized on opposite sides of the ribbon. We will also consider the spin polarization of the electron density.
ATK 10.8 does not yet have the functionality to compute Bloch states. It will be added soon, however.
Download tutorial (PDF)
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graphene_ribbon.py
spinpoldensityplot.py
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Work function of metal surfaces
ATK can be used to accurately compute the work function of metal surfaces. This tutorial describes in detail how to set up and run such a calculation.
This tutorial is courtesy of Cybernet Systems Co.
The work-flow in this tutorial applies to ATK 2008.10. It will be updated to cover version 10.8 soon.
Download tutorial (PDF)
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work_function.py
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Electron transport through monovalent atomic wires
How to compute the conductance of metallic atomic wires, complete with analysis of the transmission spectrum and k-point resolved transmisson coefficients. Inspired by Y. J. Lee et al., PRB 69, 125409 (2004).
The work-flow in this tutorial applies to ATK 2008.10. It will be updated to cover version 10.8 soon.
Download tutorial (PDF)
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GoldMonowires_Scripts.zip
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Transmission coefficients
This slightly more advanced tutorial focuses on a very specific topic: how to most efficiently compute and plot the k-point resolved transmission coefficients. In particular, we show how to take advantage of symmetries in the system, which sometimes can reduce the computational burder significantly.
The work-flow in this tutorial applies to ATK 2008.10. It will be updated to cover version 10.8 soon.
Download tutorial (PDF)
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transmission_scripts.zip
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Publications 
