First-principles study of bulk and surface oxygen vacancies in SrTiO3 crystal V. E. Alexandrov, E. A. Kotomin, J. Maier and R. A. Evarestov Eur. Phys. J. B, 72 1 (2009) 53-57 Published online: 10 October 2009 DOI: 10.1140/epjb/e2009-00339-4