First-principles study of correlation effects in VO₂

We present a first-principles study of VO₂ in the rutile and monoclinic (M₁) phases by means of all-electron full-potential linear muffin-tin orbital GW calculation. Full frequency dependence and off-diagonal matrix elements of the self-energy are taken into account. As a result of dynamical correlations, a satellite structure is found above the t_2g quasiparticle peak, although not below, in both the rutile and monoclinic phases. For the monoclinic structure, the insulating state is not obtained within the usual one-shot GW calculation. We have performed a simplified “self-consistent” GW scheme by adding a uniform shift to the conduction-band levels and recalculating the quasiparticle wave functions accordingly. An insulating solution with a gap of approximately 0.6 eV is obtained, in agreement with experiments.