The ab initio linear muffin-tin orbital method combined with density functional theory (local approximation) and the semi-empirical method of the intermediate neglect of differential overlap method based upon the Hartree-Fock formalism were used for the study of F centers and hole polarons in KNbO3 perovskite crystals. The results of calculations for SrTiO3 (100) surface relaxation with different terminations (SrO and TiO2), obtained by using an ab initio method based upon Hartree-Fock and density functional theory formalisms, were presented. The results were compared with previous ab initio and shell model calculations and low-energy electron diffraction data.

Modeling of Defects and Surfaces in Perovskite Ferroelectrics. G.Borstel, R.I.Eglitis, E.A.Kotomin, E.Heifets: Journal of Crystal Growth, 2002, 237-239[1], 687-93