Inclusion of the correlation short-range order in Ab initio calculations of the energy of the ground state by example of titanium monoxide TiO1.0

Abstract

A variant of the distribution of structural vacancies at which the crystal structure of ordered compounds simultaneously has a long-range order and correlation short-range order has been proposed and analyzed. The long-range order determines the fraction of vacancies in the atomic and vacancy sublattices of the superstructure formed because of ordering. The correlation short-range order takes into account energy favorable correlations in the arrangement of vacancies, which exist in disordered phases and are not determined by the long-range order. The possibility of the correlation short-range order has been examined by ab initio methods by example of ordering of vacancies in titanium monoxide TiO1.0 according to the type of monoclinic superstructure M5X5mon. It has been shown that partially ordered modifications with the correlation short-range order are energetically favorable as compared to the modifications without the correlation short-range order.