First-Principles Study of Correlation Effects in VO2: Peierls vs. Mott-Hubbard

TL;DR

This study uses advanced GW calculations to analyze correlation effects in VO2, revealing a satellite structure and successfully modeling the insulating phase with a 0.6 eV gap.

Contribution

It introduces a simplified self-consistent GW approach that captures the insulating state of VO2, improving upon standard 1-shot GW methods.

Findings

Satellite structure above the quasiparticle peak due to correlations

Standard GW fails to produce an insulator for monoclinic VO2

Self-consistent GW yields a 0.6 eV band gap consistent with experiments

Abstract

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.