GW approximation with LSDA plus U method and applications to NiO, MnO, and V2O3

A GW approximation (GWA) method named U+GWA is proposed, where we can start GWA with more localized wave functions obtained by the local spin-density approximation (LSDA)+U method. Then GWA and U+GWA are applied to MnO, NiO, and V2O3 in antiferromagnetic phase. The band gaps and energy spectra show excellent agreement with the experimentally observed results and are discussed in detail. The calculated width of d bands of V2O3 is much narrower than that of the observed one which may be a mixture of t(2g)(2) multiplet and single-electron t(2g) level. GWA or U+GWA does not work also in the paramagnetic phase of V2O3 and the reason for this is clarified. The method of the unique choice of on-site Coulomb interaction is discussed in detail. The criterion for whether we should adopt GWA or U+GWA is discussed and is assessed with the help of the off-diagonal elements of the self-energy.