Energy levels of oxygen vacancies in BiFeO3 by screened exchange

The oxygen vacancy in BiFeO3 is calculated to be a double donor with states 0.6 eV below the conduction band edge, consistent with cathodoluminescence and electronic conductivity data. The atomic configurations were relaxed using the local density approximation plus Hubbard U (LDA+U) to the electron-correlation energy for each defect charge state to ensure that the oxide had a nonzero band gap. The defect formation energies were calculated using the screened exchange (sX) functional.