QuantumATK packages a powerful set of tools for calculating properties of nano-scale systems. These atomic-scale calculators are based on density functional theory, semi-empirical tight binding, and classical potentials. The non-equilibrium Green’s function method is a unique feature of QuantumATK; it allows simulations on nano-scale devices and interfaces, including support for non-zero bias between the electrode leads and device components such as electrostatic gates and dielectrics. More information may be found at the QuantumATK website.
ATK is controlled using ATK-Python, which is an extension to the well-established Python scripting language. Setting up and executing QuantumATK calculations is therefore done in an ATK-Python script or directly from the command line in an interactive Python shell.
The main purpose of this manual is to document all QuantumATK functionality. The QuantumATK Reference Manual therefore gives a detailed summary of all input and output parameters, as well as notes on relevant theory and usage examples.
We also provide a thorough exposition of the theoretical background for the atomic-scale simulators implemented in QuantumATK (see Atomic-Scale Calculators), and a detailed introduction to Python scripting and using ATK-Python to control QuantumATK (see Python in QuantumATK).
For tutorials on how to use QuantumATK we refer to the Tutorials website.
New in QuantumATK Q-2019.12¶
The Q-2019.12 release of QuantumATK introduces a range of new features and performance improvements. The list below provides an introduction and, in most cases, direct links to the documentation for some of the most significant new features.
Plane-Wave Calculator is now ready for production calculations
PAW method for the Plane-Wave Calculator
ForceField: Improved MPI for force-field calculations
General improvements in algorithm for domain decomposition, MPI communicators and others. Python overhead is now reduced by 50%, which is significant at many threads.
NEGF: Device calculators
Transverse electrode repetitions
For electrodes that are pure repetitions in the lateral directions perpendicular to the transport direction, QuantumATK can automatically detect this and reduce the electrode’s lateral dimensions to that of its minimal lateral unit cell. This makes the calculation of the corresponding self-energies of the electrodes much cheaper computationally. In the Builder and Viewer, this is indicated by dashed lines in the electrode, similar to the dashed lines indicating the electrode extension in the central region.
Parallelization over left/right self energies is now implemented in QuantumATK, allowing for memory reduction of up to 30% and computational time reduction of up to 50%.
Improvements for electron mobility and electron-phonon coupling calculations
- The symmetries of the Brillouin zone are now taken into account for the
k-point sampling in the
ElectronPhononCouplingcalculations. This significantly reduces the computational time.
- It is now possible to compute metal resistivity using a constant mean-free
path. The mean-free path can either be assumed or computed.
- Automatic band selection is now possible for electron-phonon coupling calculations.
- It is now possible to calculate the thermal velocity of electrons and holes.
- The symmetries of the Brillouin zone are now taken into account for the k-point sampling in the
k.p method for band structure calculations
Density of States: Extra functionality
QuantumATK now allows for normalization of the density of states by the number of atoms, as well as for calculation of the carrier concentration of the specified contribution. See
Local Density of States
New analysis object. Calculate the density of states corresponding to a specific range of electronic energies, bands, and k-points. Useful for simulating STM images within the Tersoff-Hamann approximation. See
Partial electron density
Calculate the electron density corresponding to a specific range of electronic energies, bands, and k-points. May be used for simulating STM images. See
Bulk Transmission Spectrum now uses Green’s function
This feature enables calculation of
TransmissionSpectrumand related conductance for bulk materials without and with spin-orbit coupling included, and also improves accuracy over the previous method.
Custom mesh cutoff for Grid analysis objects
This feature allows obtaining better resolution in various analyses represented on a grid, e.g. potentials and densities, without having to re-run the SCF calculation.
Projections in EffectiveBandstructure
QuantumATK now allows for computing the
GilbertDampingtensor. This method is based on a simple physical picture: spin-orbit interaction induced non-equilibrium state of a magnetic system that relaxes to equilibrium via the electron-phonon coupling.
Calculate orbital magnetic moments in a bulk, see
Optical and Electro-optical properties of materials
Static dielectric tensor including ionic contributions
You can now calculate the full static dielectric tensor, including both electronic and ionic contributions. See
Calculate the Raman tensor and spectrum for incoming light scattered in a bulk or 2D material. See
Nuclear magnetic resonance (NMR) spectroscopy - beta version
LO/TO splitting of phonon band structure
ElectroOpticalTensorthat describes the Pockels effect, which is a change in the static dielectric constant in the presence of an electric field.
Second Harmonic Generation Susceptibility
SecondHarmonicsGenerationSusceptibility, which is the nonlinear response function describing the second harmonic generation.
Dynamics and Optimization
Improved logging for Molecular Dynamics
QuantumATK now has improved logging from MD simulations, which now show reservoir vs. instantaneous temperature (NVT) and pressure (NPT) in the log. These quantities can now also easily be shown in movie tool.
In MD simulations, it is now possible to measure any quantity at a user-defined interval. QuantumATK comes with a pre-defined list of f.ex. the various stress, strain and pressure components, but users can define their own quantities. See
It is now possible to calculate the specific heat capacity in the quasi-harmonic regime, directly from a MD simulation with relatively few atoms. See
Custom fitness criteria for crystal structure prediction
The crystal structure prediction function now accepts a user-defined fitness function which can include any combination of material properties, for example both the enthalpy and a target band gap. See
Geometry optimization improved
OptimizeGeometry can now automatically restart the geometry optimization from a previous run, has a new option for geometry optimization at constant volume, and by default removes any drift force from numerical noise, to keep the center of mass fixed in the system. See
Polymer Science and Engineering
Building and equilibrating polymer melts
The new polymer builder enables polymer melts to be built from sequences of monomers. It is possible to embed molecules, nanoparticles and surfaces in a melted polymer. Initial polymers are randomly generated by polymer Monte Carlo, then force-capped molecular dynamics follows to relax the atomic overlaps and too-close atoms. See Polymer Builder,
A Polymer Equilibration study object accelerates the equilibration of polymers using cycles of high-temperature and high-pressure simulations. See
Potentials for polymer models
Installing and running the software¶
The QuantumATK binary installer is available for registered users at the SolvNet software portal. Access to a valid QuantumATK license is also needed. Detailed instructions are given in the Installation Guide. Note that an evaluation license may be requested using the Synopsys Eval Portal.
When QuantumATK has been installed on your machine you can run it from the command line
using the atkpython executable, which should be in your
a properly prepared QuantumATK Python script (written in ATK-Python):
$ atkpython script.py
You can download and use
script.py to test this –
the script defines a water molecule and relaxes the atomic coordinates using the
BFGS algorithm to minimize the forces.
How to read this manual¶
This manual is typeset using in-line references to QuantumATK Python objects and functions, and contains several script examples. The following style conventions are used:
All QuantumATK objects and functions appear as links, e.g.
MoleculeConfiguration. The link will take you to the relevant section of the QuantumATK Reference Manual, where a detailed description of the object “MoleculeConfiguration” is provided.
Boldface letters are used to highlight specific words, e.g. atkpython, while in-line names of Python variables, functions, parameters, and methods are in general typeset using a monospace serif, e.g.
list_of_atomsfor a Python variable and
cartesianCoordinates()for a method of the
In-line names of files and directories are also typeset using a monospace serif, e.g.
Python structures are visually enclosed in a box and typeset using a monospaced serif:
# This is a comment for i in range(3): print(i)
Scripts can often be downloaded by following a link, e.g.
Instructions for using the command line are indicated by the
$ atkpython script.py
while instructions for using an interactive Python session is indicated by the
>>> myList = [1, 2, 3, 4, 5] >>> print(myList) [1, 2, 3, 4, 5] >>> print(len(myList)) 5