Pressure-induced phase transition in MgS an ab initio constant pressure study

We study the pressure-induced phase transition of MgS using a constant pressure ab initio technique and predict for the first time a structural phase transformation from the rocksalt structure to a CsCl-type structure with the application of hydrostatic pressure. We also characterize the transformation mechanism and propose two intermediate phases having pnam and snsn symmetries for the rocksalt-to-CsCl type phase transformation of MgS, which is different from the previously proposed mechanisms. Furthermore, we study this phase transition using the total energy calculations. Our predicted transition parameters and bulk properties are in good agreement with the previous first principle calculations.