It was recalled that theoretical calculations of defect properties, especially transition energy levels, were typically performed using first-principles density-functional theory methods using super-cells of finite size. So far, three approaches, band-filling corrections, band-edge corrections and no corrections had been applied to deal with the potential inaccuracy caused by the finite size. These three approaches were compared here by calculating the (0/2+ ionization energies of the oxygen vacancy (VO) in In2O3 and ZnO. It was found that a correction must be included whether or not the defect level was deep or shallow, especially when the defect band had a large dispersion. The band-filling correction approach gave the best correction. The band-edge correction approach worked well in GGA calculations only for certain systems in which the band gap underestimation was partially corrected by choosing effective band edges.

Comparative Study of Defect Transition Energy Calculation Methods: the Case of Oxygen Vacancy in In2O3 and ZnO. Yin, W.J., Ma, J., Wei, S.H., Al-Jassim, M.M., Yan, Y.: Physical Review B, 2012, 86[4], 045211