First-principles techniques were used to study vacancy-O complexes. Substitutional O was found to be an off-site defect, in agreement with experiment. It exhibited one high-frequency O-related local vibrational mode at 788/cm. The VO2 defect had D2d symmetry and only one O-related high-frequency infra-red active mode, at 807/cm. The VO3 defect had 3 high-frequency infra-red active modes. The V2O defect had one such local vibrational mode. The results provided strong support for the attribution of the 889/cm (300K) local vibrational mode to VO2.

C.P.Ewels, R.Jones, S.Oberg: Materials Science Forum, 1995, 196-201, 1297-302