Abstract
Elpasolite is the predominant quaternary crystal structure ( prototype) reported in the Inorganic Crystal Structure Database. We develop a machine learning model to calculate density functional theory quality formation energies of all pristine elpasolite crystals that can be made up from main-group elements (up to bismuth). Our model’s accuracy can be improved systematically, reaching a mean absolute error of for a training set consisting of crystals. Important bonding trends are revealed: fluoride is best suited to fit the coordination of the site, which lowers the formation energy whereas the opposite is found for carbon. The bonding contribution of the elements and is very small on average. Low formation energies result from and being late elements from group II, being a late (group I) element, and being fluoride. Out of crystals, 90 unique structures are predicted to be on the convex hull—among which is , with a peculiar stoichiometry and a negative atomic oxidation state for Al.
- Received 24 August 2015
DOI:https://doi.org/10.1103/PhysRevLett.117.135502
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Published by the American Physical Society