Formation of localized hole states in complex oxides .1. Hole states in BaTiO3

Defect electrons (holes) play an important role in most technologically important complex oxides. In this contribution we present the first detailed characterization of localized hole states in such materials. Our investigations employ advanced embedded-cluster calculations which consistently include electron correlations and defect-induced lattice relaxations. This is necessary in order to account for the variety of possible hole-state manifestations. Even in highly ionic oxides such as MgO, there exists a delicate interplay between electron correlations and defect-induced lattice deformations.