First-principles calculations were made of point defects in the rutile phase. Both O vacancies and Ti interstitials were considered. The size effect of the super-cell was examined and the localized state associated with the O vacancy was found to be sensitive to the super-cell size. It was also found that the O vacancy did not give rise to a defect level within the energy gap, while the Ti interstitial created a localized state 0.2eV below the conduction edge that could be related to infra-red absorption data. Charge accumulation around the O vacancy was attributed to the polarization of valence bands.

First-Principles Study of Point Defects in Rutile TiO2–x. Cho, E., Han, S., Ahn, H.S., Lee, K.R., Kim, S.K., Hwang, C.S.: Physical Review B, 2006, 73[19], 193202