Stress dependence of structure, electronic and optical properties of BaTiO3 from WC, VdW-DF-C09 and HSE functional calculations

Abstract

The optimization of a BaTiO3 crystal unit cell was realized with the WC and VdW-DF-C09 exchange-correlation functional, under different hydrostatic pressures from –10 to 10 GPa with step size of 5 GPa. As part of the results, changes in the crystal lattice parameters and volume are presented and discussed, as well as changes in the different Ba-O and Ti-O bond lengths. Self-consistent calculations (SCF) were performed using HSE functional in order to obtain electronic band structure, density of state (DOS) and optical properties. Löwdin charge analysis, related to charge transfer of Ba, Ti, and O, shows the details of the atomic bonds as function of the hydrostatic stress, including the contribution of empty orbits such as the 6p, 5d and 4f from Ba atoms, 3d and 4f from Ti atoms and 3d and 4f from O atoms. Finally, the imaginary part of the complex dielectric function, in the energy range from 0 to 15eV, is presented and discussed.