Abstract
The electrical and optical properties of Barium Titanate BaTiO3 and lithium niobate LiNbO3 single crystals at room temperature are theoretically calculated by using a microscopic model based on the orbital approximation in correlation with the dipole-dipole interaction. We find that for LiNbO3 both the electronic polarizabilities and the electronic hyperpolarizabilities have to be considered in this calculation in order to match both the spontaneous polarization and refractive indices with experimental data. For BaTiO3 a description based an the electronic polarizability is sufficient.
Acknowledgements
This work was supported by the DFG under grant Nrs. EN 434/7-1 and EN 434/2-3.