Electronic and structural properties of alkaline-earth oxides under high pressure

The linear muffin-tin-orbital method in its tight-binding representation is used to calculate the band structures and to investigate the structural phase stability of MgO, CaO, and SrO under high pressures. The calculated equilibrium properties agree well with the experimental data. In CaO and SrO, the B1-B2 transition occurs at 557 and 317 kbar, respectively, which are in agreement with the experimental observations. For MgO the transition from the B1 to B2 phase is found to occur at a very high pressure of 1975 kbar. The electronic band structures at normal and at high pressures and the variation of fundamental band gaps as a function of pressure are calculated.