Effect of off-diagonal dielectric response on optical properties of LaTiO3

Optical spectra of LaTiO3 are analyzed on the basis of an ab initio macroscopic dielectric function. The energy band structure and microscopic dielectric matrix are calculated with the extended linear augmented plane wave (ELAPW)-k · p method. The origin of UV spectral structures is elucidated. LaTiO3 is compared with SrTiO3 and BaTiO3 perovskites, and chemical trends in the formation of the UV reflectivity are discussed. The inclusion of local field corrections shifts spectral structures due to semi-core La 5p and Ti 3p excitations by several eV to higher energies. Calculated reflectivity and optical conductivity curves agree well with the experiment. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)