Density functional calculations of the electronic structure and optical properties of magnesium oxide

Abstract

The electronic structure and optical properties of magnesium oxide (MgO) are investigated at the structural phase transition pressure using the plane-wave pseudo-potential density functional method within the generalized gradient approximation (GGA). Good agreement between the calculated lattice parameters and experimental results is obtained, and a direct energy gap of 3.72 eV is estimated in the GGA for the NaCl structure (B1) of MgO. The electronic structure of the CsCl-type structure (B2) is predicted near the structural phase transition pressure for the first time and discussed in detail. The dielectric function and optical properties such as reflectivity, absorption coefficient, refractive index, and electron energy-loss function are presented in a wide energy range between 0 and 60 eV. It is found that the reflectivity spectrum and energy-loss spectrum of the B1 phase at 0 GPa are consistent with experimental results.