The electronic structure of the O vacancy in ZnO was found to be sensitive to the corrections applied to the local (spin) density approximation (LSDA) band gap underestimate. Here, the “LSDA+U” approach, in which Hubbard-U corrections were added to the local density approximation, was applied to both Zn d and Zn s orbitals. The justification of this approach was considered. Transition state energies were calculated self-consistently instead of applying a posteriori corrections. The super-cell size dependence and applicability of Makov–Payne corrections was investigated and an extrapolation approach inversely proportional to the cell volume was used. The 0/2+ transition level was found at 0.80eV above the valence-band maximum and a small negative U behavior was obtained with U=−0.05eV. The Kohn–Sham one-electron levels in the different charge states were also presented and relevant experimental results were considered.

First-Principles Calculation of the O Vacancy in ZnO - a Self-Consistent Gap-Corrected Approach. T.R.Paudel, W.R.L.Lambrecht: Physical Review B, 2008, 77[20], 205202 (9pp)