Bulk properties and electronic structure of SrTiO3, BaTiO3, PbTiO3 perovskites: an ab initio HF/DFT study

The results of detailed calculations for bulk properties and the electronic structure of the cubic phase of SrTiO3 (STO), BaTiO3 (BTO), and PbTiO3 (PTO) perovskite crystals with detailed optimization of basis set (BS) are discussed. These are obtained using ab initio Hartree–Fock (HF) and density functional theory (DFT) with Hay–Wadt pseudopotentionals based on localized, Gaussian-type BS. A number of different exchange–correlation functionals including hybrid (B3PW and B3LYP) exchange techniques are used. Results, obtained for seven methods, are compared with previous quantum mechanical (QM) calculations and available experimental data. Especially good agreement with the experimental data has been achieved for hybrid functionals. With the polarization orbitals added to the BS of oxygen atom, the calculated optical band gaps are 3.57, 3.42 and 2.87 eV for STO, BTO and PTO respectively, in very good agreement with experimental data.