Oxygen vacancy in perovskite oxides: Electron structure calculation by the SCF Xα, SW technique

Abstract
The electron structure of the oxygen vacancy in SrTiO3 has been computed for the first time in frames of the approach that does not use a basis. The SCF Xα SW technique is used for this purpose. The clusters considered have 4 coordination spheres included. A satisfactory agreement with experiment is obtained for the cluster modeling the ideal crystal. It is found that the lowest unoccupied state of the cluster modeling the double-charged oxygen vacancy V++ o is of the alg symmetry, and it is localized in the sphere of vacant site for 34%, in cation spheres -for 20%. The potential reaches its maximum value in the vicinity of vacancy center. It means that a strong localization of an alg-state in the vicinity of V++ o is possible only due to the multiple scattering of the electron wave at the nearest neighbors. Perovskite, oxygen vacancy, electronic structure.