Old puzzle of incommensurate crystal structure of calaverite AuTe2 and predicted stability of novel AuTe compound
Abstract
It is shown that the long-standing puzzle of incommensurate crystal structure of AuTe2 can be solved, if this material is considered as a negative charge-transfer system. Using modern computational methods, we demonstrate that charge redistribution associated with incommensurate modulations of crystal structure occurs not so much on Au, but predominantly on Te sites. This substantially reduces Coulomb energy costs for creating such a unique crystal structure. The same mechanism also explains superconductivity of doped AuTe2. Exploring different Au-Te compositions, we also discovered a previously unknown compound AuTe, which theoretically is very stable, and we predict its crystal structure.
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