Improved calculation of the electronic and optical properties of tetragonal barium titanate

Abstract

The electronic and optical properties of tetragonal barium titanate (BaTiO3) have been investigated by use of first-principles density functional theory on a plane wave basis, by use of norm-conserving pseudopotentials in the localized density approximation. For accuracy, experimental lattice parameters reported in the literature were used. The band structure, total and partial density of states (DOS), and Born effective charges of tetragonal BaTiO3 were obtained from first-principles calculations. The partial DOS and Born effective charges indicate that the Ti–O bonds are partially covalent and the Ba–O bonds are partially ionic. The complex dielectric functions for ordinary and extraordinary optical polarization were calculated, and were in reasonable agreement with those from previous first-principles calculations. The refractive index, extinction coefficient, reflectivity, and energy-loss spectrum for both types pf polarization were calculated from the complex dielectric function; the results obtained were an improvement on other published results.