STRUCTURAL, ELECTRONIC AND OPTICAL PROPERTIES OF THE TETRAGONAL PHASE OF CaSiO3 PEROVSKITE UNDER PRESSURE: FIRST-PRINCIPLES CALCULATIONS

First principles studies of structural, elastic, electronic and optical properties of tetragonal CaSiO3 perovskite under pressure are reported using the pseudopotential plane wave method within the local density approximation (LDA). The calculated equilibrium lattice is in good agreement with the available experimental data. The elastic constants and their pressure dependence are calculated using the static finite strain technique. A linear pressure dependence of the elastic stiffnesses is found. Band structures show that tetragonal CaSiO3 perovskite is a direct band gap material. In order to understand the optical properties of tetragonal CaSiO3 perovskite, the dielectric function, absorption coefficient, optical reflectivity, refractive index, extinction coefficient, and electron energy loss are calculated for radiation up to 40 eV. This is the first quantitative theoretical prediction of the elastic, electronic and optical properties of tetragonal CaSiO3 perovskite, and it still awaits experimental confirmation.