Polaronic configurations that were introduced by oxygen vacancy in rutile TiO₂ crystal have been studied by the DFT + U method. It is found that the building block of TiO₆ will expand when extra electron is trapped in the central Ti atom as polaron. With manually adjusting the initial geometry of oxygen vacancy structure, a variety of polaronic configurations are obtained after variable-cell relaxation. By calculating different sizes of supercell model, it is found that the most stable configuration can be influenced by the density of oxygen vacancy. With increasing interaction between vacancies, the most stable polaronic configuration change from small polaronic configuration to mixed configuration.
Keywords: DFT + U; electronic structure; oxygen vacancies; polarons; rutile.