A new parametrization was developed for the classical shell model for the cubic phase of the perovskite, and was used to calculate the structural, elastic and dielectric properties of the material. By using this parametrization, the defect formation and migration energies, and atomic displacements, were calculated. At the same time, the quantum mechanical method of intermediate neglect of differential overlap was applied to the same problem. The migration energies for the O vacancy, which were obtained by using these quite different methods, were quite close (0.68 and 0.79eV, respectively). They also agreed with the only available experimental estimate (1eV). The atomic relaxations which were calculated by using the 2 methods agreed quite well.

Semi-Empirical Defect Calculations for the Perovskite KNbO3. P.W.M.Jacobs, E.A.Kotomin, R.I.Eglitis: Journal of Physics - Condensed Matter, 2000, 12[5], 569-74