First-principles study of correlation effects in VO2

We present a first-principles study of VO2 in the rutile and monoclinic (M-1) 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.