software
Which software can do ab initio calculations for you? Which software can solve Schrödinger’s equation? This graphical compilation of logos tells you there are many of them on the market:
Somewhat more quantitative information can be found on this Wikipedia page (you can sort the table according to your preferred column).
Out of this list, we’ll pick just one code to work with in this course. For the time being, that’s Quantum Espresso (support for other codes will be added in future versions of this course). The main reasons for taking this one is that it has a good reputation, has a large developpers and user community behind it, runs on different computers and operating systems (even on your off-the-shelf Windows laptop), and is free of cost (GPL license). Whatever you learn in this course with Quantum Espresso, you can use later again, wherever you’ll work or study. There are many other codes, though, that fulfill most or all of these criteria too. If you are somewhat familiar with another code and you want to use this course to sharpen your skills about your preferred code, feel free to do so. (And if you want to contribute to this course by translating the how-to instructions for specific tasks to your preferred code, you are most wellcome to do that.)
This is a good time to download and install it the DFT code you are going to use in the coming weeks. The procedure can be found in the first item of ‘let’s play’. Please go there and do this before the next feedback webinar. But first finish the current chapter – you’re almost there.
As many codes with an academic origin, Quantum Espresso is operated with a command line. Many people nowadays prefer graphical interfaces instead. Therefore, we will use in this course the semi-commercial graphical interface NanoLab. One of its attractive features is that the same interface can command different ab initio codes. We will use it to work with Quantum Espresso, but if you later work in a place where they prefer VASP, you can use VNL in almost exactly the same way with VASP. NanoLab is free for academic use (a special registration is required). If you are not working in academia, you can use a 4-month free trial version, which should be enough to cover the duration of this course. (note added: VNL is currently — 2019 — not free any longer for academic use. This might be restored in the future, but it’s unclear. Instructions are updated to work around NanoLab. Where possible, the NanoLab instructions remain in place for people who would have already a paid license. Apologies for the inconvenience.)
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