Surface Electronic Structure of SrTiO3 Studied by the DV-Xα Cluster Method

The electronic structure of SrTiO 3 (100) surface is investigated by the DV-Xα cluster method. It is demonstrated by the first principle, calculations that the intrinsic deep surface states do not exist on this surface. On the other hand the possibility of the three types of shallow surface states is suggested; A) those derived from x z , y z like d orbitals of surface Ti, B) those coming from 3 z 2 - r 2 like d orbital admixed with 4 p z , 4 s orbitals of surface Ti, and C) those associated with the surface O 2 p orbitals. The energy and properties of the localized electronic states induced by surface and bulk oxygen vacancies are calculated and compared with recent UPS and ELS experiments.