Theory of anisotropic oxygen polarizability in the tetragonal phase of BaTiO3

Anisotropic oxygen polarizability in the tetragonal phase of BaTiO 3 , is discussed taking into account of dipole-dipole interaction due to the electronic polarization and the lattice deformation. In this microscopic model, we have assumed that the dominant source of the optical properties is the anisotropy of the oxygen polarizability, particularly the contribution of the oxygen O z . It is found that the calculated results are in good agreement with the experimental data.