First-Principle Calculations for Transition Phase and Elastic Properties of SrS

Abstract

The transition phase and elastic properties of SrS from NaCl structure (B1) to CsCl structure (B2) are investigated by ab initio plane-wave pseudopotential density functional theory method and by the quasi-harmonic Debye model. The transition pressure varies non-linearly with temperature, and the pressure of the mechanical instability increases linearly with increasing temperature. It is shown that the B1 structure SrS is a most elastically anisotropic mineral at any pressure. The Debye temperature, the heat capacity, thermal expansion and Grüneisen parameter over a wide range of pressures and temperatures are also obtained.