Electronic structure of perovskite-type transition metal oxides La M O 3 ( M = Ti ∼ Cu ) by U + GW approximation

We investigate electronic structures of $\text{La}M{\text{O}}_{3}$ $(M=\text{Ti}\ensuremath{\sim}\text{Cu})$ systematically by means of $\text{U}+\text{GW}$ approximation. In these strongly correlated systems, it is important to treat large on-site Coulomb interactions and their dynamical screening effects. Transition-metal ions in perovskite-type lanthanum oxides are trivalent and their physics is qualitatively different from that of divalent transition-metal ions in transition-metal mono-oxides. The localization of wave functions of $\text{La}\text{ }4f$ and $3d$ orbitals of Ti, V, and Co is crucial. On the other hand, the screening effect for other transition-metal $3d$ orbitals is strong enough so as to reduce the on-site static-screened Coulomb interaction in trivalent oxides. The band gaps, the magnetic moments, and energy spectra are discussed in comparison with the experimentally observed results. Calculated energy spectra of $\text{La}M{\text{O}}_{3}$ $(M=\text{V}\ensuremath{\sim}\text{Cu})$ are in good agreement with experimental results.