High-pressure behavior of MgO: Structural and electronic properties

Abstract

The high-pressure behavior of the structural and electronic properties of MgO is examined with use of the pseudopotential method within local-density theory. At zero pressure the rocksalt phase is found to be lower in energy than a hypothetical CsCl structure. However, we predict a phase transformation into an insulating CsCl structure at a very high hydrostatic pressure of about 10 Mbar. This result predicts that the CsCl phase for MgO is unlikely to exist even in the lower mantle of the Earth. The calculated ground-state properties such as lattice constant, bulk modulus, and cohesive energy for the rocksalt phase are in good agreement with experiment. The electronic band structures at normal and high pressures are also given.