Electronic structure of the $M\mathrm{O}$ oxides $(M=\mathrm{Mg},$ Ca, Ti, V) in the GW approximation

The quasiparticle band structures of nonmagnetic monoxides $M\mathrm{O}$ $(M=\mathrm{Mg},$ Ca, Ti and V), are calculated by the GW approximation. The band gap and the width of occupied oxygen $2p$ states in insulating MgO and CaO agree with experimental observation. In metallic TiO and VO, conduction bands originated from metal $3d$ states become narrower. Then the partial densities of transition metal $e_g$ and $t_{2g}$ states show an enhanced dip between the two. The effects of static screening and dynamical correlation are discussed in detail in comparison with the results of the Hartree-Fock approximation and the static Coulomb hole plus screened exchange approximation. The $d-d$ Coulomb interaction is shown to be very much reduced by on-site and off-site d-electron screening in TiO and VO. The dielectric function and the energy loss spectrum are also presented and discussed in detail.