Structural phase transition, electronic and elastic properties of SrSe under pressure from first-principles calculations

First-principles pseudopotential calculations have been performed to investigate the structural phase transition, electronic and elastic properties of SrSe considering several possible structural phases. Our calculations show that SrSe crystalizes in NaCl-type (B1) structure at ambient pressure and undergoes first-order phase transition to CsCl-type (B2) structure at 13.7 GPa with a relative volume collapse of 10.37%, and no further transition is found up to 40 GPa, the highest pressure attempted in the calculations. For metastable phase, SrSe prefer h-MgO instead of wurtzite (B4) structure, which is consistent with the fact that the ionic compound prefers a high coordination. The influence of the crystallographic structure and the hydrostatic pressure on elastic constants and energy band structures of SrSe have also been investigated. Our calculated results are discussed and compared with available experimental and theoretical data.