Energetics of oxygen vacancies at rutile TiO2(110) surface

Density functional theory and a projector-augmented wave method are applied to study defected TiO2(110) surface. Three types of a single oxygen vacancy created in surface and in subsurface layers are examined. The variation of the vacancy formation energy and the changes in structural and electronic properties of oxygen-deficient rutile surface are investigated as a function of the vacancy depth. We find that the formation of bridging and sub-bridging O vacancies in odd layers of the slab is favored over even layers.