Quantum Chemical Study of the TiO₂ Surfaces

A tight-binding extended Huckel (TBEH) calculation has been performed to investigate the electronic structure of the TiO₂ surfaces. By analysing the density of states (DOS) of various surfaces and the orbital interactions between surface atoms, it is found that the continuing drop of the uppermost valence band peak along with the increasing surface defects is due to the removal or surface birdge O atoms. and that the interaction of the two Ti atoms adjacent to the O vacancy induces a defect gap state.