Mgs And The First Principle Of Mgse Properties Studied

Based on density function theory, the electronic structure, elastic properties and optical properties of the MgS and MgSe crystal in rocksalt (RS) and zinc blende (ZB) phases under different pressures were investigated The results indicated that with an increase of pressure for two structures, the Mg-S/Mg-Se bonds became shorter, the charge transfer decreased, the conduction band shifted to higher energy. Compared to MgS and MgSe at 0 GPa, the curves of the dielectric functions, absorption coefficients and electron energy-loss functions of the two phases showed finer structures. With an increase in pressure, the absorption coefficient increased while the absorption edges and the absorption peaks of the absorption curves as well as the peaks of the energy-loss functions showed a blue shift to some extent.The computed elastic constants agree well with others theory values. The brittleness and ductility of the two phases MgS and MgSe are evaluated based on obtained elastic constant and empirical criterion. The results shown that ZB MgS and MgSe are brittleness, and that RS phase MgS and MgSe are ductile.In addition, the lattice-dynamical properties, the thermal expansion coefficient and heat capacity for MgS and MgSe crystalline are investigated using density-function perturbation theory (DFPT).