Exploring, fitting, and characterizing the configuration space of materials with multiscale universal descriptors

Descriptors of the environment of an atom in a material give a similarity metric between different structures, to be used in interatomic potentials or for analyzing patterns in large sets of atomistic configurations. Since different species have different typical bond lengths, the length scales that optimally describe them also differ. We present heuristics for a universal set of multiscale Smooth Overlap of Atomic Positions (SOAP) descriptors. They describe short range interactions precisely, include longer range interactions more approximately, handle the diversity of hetero-atomic length scales, and are stable when new species are added. Using them we have extended our automatic interatomic potential generation method [1] to multicomponent systems, implemented in a simple python workflow for structure search, configuration selection, and reference energy calculations required for the fit. We present results for generated single and multi-species potentials, and use the same descriptors to analyze the diversity in the generated databases.

[1] Bernstein et al., npj Comput. Mater. v. 5, 99 (2019)