Evolutionary search for superhard materials: Methodology and applications to forms of carbon and TiO2

Andriy O. Lyakhov, Artem R. Oganov

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197 Citations (Scopus)

Abstract

We have developed a method for prediction of the hardest crystal structures in a given chemical system. It is based on the evolutionary algorithm USPEX (Universal Structure Prediction: Evolutionary Xtallography) and electronegativity-based hardness model that we have augmented with bond-valence model and graph theory. These extensions enable correct description of the hardness of layered, molecular, and low-symmetry crystal structures. Applying this method to C and TiO2, we have (i) obtained a number of low-energy carbon structures with hardness slightly lower than diamond and (ii) proved that TiO2 in any of its possible polymorphs cannot be the hardest oxide, its hardness being below 17 GPa.

Original languageEnglish
Article number092103
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume84
Issue number9
DOIs
Publication statusPublished - 12 Sep 2011
Externally publishedYes

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