  We present a study of VO2 in the rutile and monoclinic (M1) phases by means
of all-electron full-potential LMTO GW calculation. Full frequency dependence
and the off-diagonal matrix elements of the self-energy are taken into account.
As a result of dynamical correlation, a satellite structure is found above the
$t_{2g}$ quasiparticle peak but not below, in both the rutile and monoclinic
phases. For the monoclinic structure, the insulating state is not obtained
within the usual 1-shot GW calculation. We perform a simplified
"self-consistent" GW scheme by adding a uniform shift to the conduction band
levels and recalculating the quasiparticle wavefunctions accordingly. An
insulating solution with a gap of approximately 0.6 eV is obtained, in
agreement with experiments.
