pyCSH: Automated atomic-level structure generation of bulk C-S-H and investigation of their intrinsic properties

A new Python code for the automated generation of realistic bulk calcium silicate hydrate (C-S-H) structures is introduced. The code was used to generate 400 structures with Ca/Si of 1.3, 1.5, 1.7, and 1.9. The generated structures are in excellent agreement with experimentally measured C-S-H properties (Ca/Si, 2H/Si, MCL, Si-OH/Si, and Ca-OH/Ca). Molecular dynamics was used to simulate the structures, which were then investigated for their structural features and energetic stability. The results indicate very similar short-range ordering and energetic stability between all 400 structures. Finally, it is shown how computational C-S-H models can be used to understand the experimentally measured pair distribution functions. The code, named pyCSH, is available as open source under GPL-2 license at GitHub https://github.com/hegoimanzano/pyCSH.git and https://github.com/akmiitm/pyCSH.git.