First-principle study of the polarization, atomic displacements and electronic structure of angular-deformed barium titanate

Abstract

The influence of β and γ angular deformation on polarization, TiO(3) bond distances, atomic displacements, number of states, valence charge distributions and valance charge asymmetry of barium titanate (BaTiO3) has been investigated using local density approximation. The results show that for all angles of 89.5°≤ β&γ ≤ 90.5°, there is a clear correlation between polarization, TiO(3) bond distances, atomic displacements and number of states of the 3dz2 orbital. For the case of γ-deformation the values of polarization and the other parameters are approximately constant in the range of 89.8°≤γ ≤ 90.2° and an abnormal behavior is observed at γ = 89.6°. In this case valence charge asymmetry of Ti 3d orbital has a direct relation with the polarization and atomic displacements of Ti atoms for the whole region of γ, especially at γ = 89.6°. In the case of β-deformation, an approximately symmetrical behavior versus β variations is observed for all above-mentioned parameters. In this case, a direct relation between valence charge asymmetry of Ti 3d orbital, polarization and atomic displacements is remarkable only for β > 89.8° and the region of β < 89.8° does not reveal such a direct relation.