How Come the QuantumATK is Larger than a Typical DFT Code

If you downloaded and installed ATK-VNL, you probably noticed it is quite a large package, about 1 GB to download and about 2 GB to install. That is because you are not just getting a bit of code for DFT calculations - QuantumATK is a complete platform for atomic-scale simulations, which even includes development tools for creating extended functionality. But let us explain this in a bit more detail. First of all, QuantumATK runs out of the box on pretty much any Windows, Linux or Mac OS X machine. There is no need for the user to compile source code, or even install any additional libraries (with a few exception on some flavours of Linux). Instead, QuantumATK is precompiled and fully optimized for both laptop and desktop graphical performance, as well as for running in HPC environments like clusters and big servers. To achieve this (which is not entirely easy!), the package needs to contain a lot of components, which takes up a bit of space. One should also note that with QuantumATK, you get not only an easy-to-use GUI and a powerful atomic-scale code; you also get a development environment that can be used to add functionality. Specifically, you get a complete Python 3.11 interpreter with several (~100) Python libraries preinstalled and ready to be used. In order to achieve maximum performance, the scientific libraries used by QuantumATK (and QuantumATK itself) are also compiled with Intel MKL, which is then shipped with QuantumATK as runtime library.

Having all these packages, readily available at their fingertips, enables users to easily develop additional functionality on top of QuantumATK. And not only for the back-engine; the user can also create new plugins in the GUI, using the provided OpenGL (with pyopengl and glew), PyQt5 (with Qt5 bindings) library (Tcl/Tk is also included). Now, as if this this was not enough, a few complete atomistic simulation code packages are also included:

  • The classical empirical potential code TremoloX - the foundation of QuantumATK ForceFields.

Finally, a large part of the package is actually taken up by data files:

  • Several pseudopotential libraries (FHI, OMX, HGH, SG15, PseudoDojo, PAW) covering the entire periodic table for DFT calculations in QuantumATK.

  • Empirical classical potential parameter sets for classical calculations (see Force Field).

  • Slater-Koster and DFTB parameter sets for semi-empirical calculations (see Semi Empirical).

With this, we hope you will appreciate why the installer package for QuantumATK is rather large! We are however constantly working on optimizing the package size to avoid it growing further, even as we add new functionality and libraries. In conclusion, you should not really compare the download of QuantumATK to, say, the source code package of Quantum Espresso or VASP. Rather, view it as something on the level of Adobe Photoshop or Microsoft Office.