Structural and electronic properties in cubic and tetragonal BaTiO3 crystal due to La impurity

The effects in BaTiO3 due to the La-doping have been studied by means of advanced quantum-chemical method based on the Hartree–Fock theory. A supercell consisting of 135 atoms has been used throughout the work. First, the effects in cubic phase of the material have been investigated after minimisation of the total energy of the crystal. The obtained relaxation energy was found to be equal to 0.94 eV. The extra electron due to the La atom was found to be situated in a local energy level within the band gap. In tetragonal phase the relaxation energy was obtained to be equal to 0.52 eV and again the extra electron is confined in the local energy level within the band gap.