Structural, elastic, electronic and optical properties of the cubic perovskites CaXO3 (X=Hf and Sn)

The structural, elastic, electronic and optical properties of CaXO3 compounds with the cubic perovskites structure have been investigated, by employing a first principles method, using the plane wave pseudo potential calculations (PP-PW), based on the density functional theory (DFT), within the local density approximation (LDA). The elastic constants and their pressure dependence are calculated using the static finite strain technique. We derived the bulk, shear and Young’s moduli for ideal monocrystalline and for polycrystalline CaXO3 aggregates which we have classified as ductile in nature. Band structures reveal that these compounds are indirect energy band gap (R-G) semiconductors; the analysis of the site and momentum projected densities, valence charge density bond length, bond population and Milliken charges, shows that bonding is of covalent–ionic nature. We have found that the elastic constants C11, C12, C44 are in good correlation with the bonding properties. The optical constants, including the dielectric function, optical reflectivity, refractive index and electron energy loss, are calculated for radiation up to 20 eV.