The electronic structure of intrinsic defects at TiO2(110) surfaces: An ab initio molecular orbital study

We report on an isolated cluster approach to determine local electronic structures of TiO2 surfaces before and after formation of intrinsic defects, i.e., oxygen vacancies, at different crystallographic sites. In particular, isolated oxygen vacancies at bridging sites, isolated oxygen vacancies at in-plane sites and aggregated oxygen vacancies at bridging sites have been treated which lead to changes in the coordination of the adjacent Ti atoms. We find that electronic band gap states are only formed in the presence of fourfold coordinated Ti surface atoms. (C) 1996 John Wiley & Sons, Inc.