Diatomic molecule as a testbed for combining DMFT with electronic structure methods such as <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>G</mml:mi><mml:mi>W</mml:mi></mml:mrow></mml:math> and DFT

Abstract

We implemented a combination of DMFT and $GW$ in its fully self-consistent way, one shot $GW$ approximation, and quasiparticle self-consistent scheme, and studied how well these combined methods perform on a ${\mathrm{H}}_{2}$ molecule as compared to more established methods such as LDA+DMFT. We found that most flavors of $GW+\mathrm{DMFT}$ break down in a strongly correlated regime due to causality violation. Among $GW+\mathrm{DMFT}$ methods, only the self-consistent quasiparticle $GW+\mathrm{DMFT}$ with static double-counting, and a method with causal double-counting, correctly recover the atomic limit at large H-atom separation. While some flavors of $GW+\mathrm{DMFT}$ improve the single-electron spectra as compared to LDA+DMFT, the total energy is best predicted by LDA+DMFT, for which the exact double-counting is known, and is static.