Appendix B Structure of the code

The bulk of this manual is concerned with the available options to build and run FHI-aims for a particular purpose. In our experience, most users will probably remain at this level in their use of the code, already due to the time constraints of a normal research schedule.

Nonetheless, we strongly believe that running a “physics” code as a complete black-box package is not a good idea. Our branch of physics is based on (mostly) well-understood differential equations, and the solution technique applied, including its limitations, must be well understood, or at least understandable, to gauge the outcome of a particular calculation. In order to achieve this, the source code to the method used must be available. While we do not expect most users to go through the code in its entirety with a fine-tothed comb, we do encourage any user to look into the source code and try to understand in which way FHI-aims produces its exact solution to a problem.

The purpose of this appendix is to facilitate this understanding, by outlining the overall structure of the code, specifically, the high-level subdivision of physical tasks.