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Discovering Superhard B–N–O Compounds by Iterative Machine Learning and Evolutionary Structure Predictions

[Image: see text] We searched for new superhard B–N–O compounds with an iterative machine learning (ML) procedure, where ML models are trained using sample crystal structures from an evolutionary algorithm. We first used cohesive energy to evaluate the thermodynamic stability of varying B(x)N(y)O(z)...

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Detalles Bibliográficos
Autores principales: Chen, Wei-Chih, Vohra, Yogesh K., Chen, Cheng-Chien
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2022
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9219054/
https://www.ncbi.nlm.nih.gov/pubmed/35755336
http://dx.doi.org/10.1021/acsomega.2c01818
Descripción
Sumario:[Image: see text] We searched for new superhard B–N–O compounds with an iterative machine learning (ML) procedure, where ML models are trained using sample crystal structures from an evolutionary algorithm. We first used cohesive energy to evaluate the thermodynamic stability of varying B(x)N(y)O(z) compositions and then gradually focused on compositional regions with high cohesive energy and high hardness. The results converged quickly after a few iterations. Our resulting ML models show that B(x+2)N(x)O(3) compounds with x ≥ 3 (like B(5)N(3)O(3), B(6)N(4)O(3), etc.) are potentially superhard and thermodynamically favorable. Our meta-GGA density functional theory calculations indicate that these materials are also wide bandgap (≥4.4 eV) insulators, with the valence band maximum related to the p-orbitals of nitrogen atoms near vacant sites. This study demonstrates that an iterative method combining ML and ab initio simulations provides a powerful tool for discovering novel materials.