Diffusion quantum Monte Carlo and GW study of the electronic properties of monolayer and bulk hexagonal boron nitride
22 Apr 2020
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Hunt R. J.
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Monserrat B.
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Zolyomi V.
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Drummond N. D.
We report diffusion quantum Monte Carlo (DMC) and many-body $GW$ calculations
of the electronic band gaps of monolayer and bulk hexagonal boron nitride
(hBN). We find the monolayer band gap to be indirect...$GW$ predicts much
smaller quasiparticle gaps at both the single-shot $G_0W_0$ and the partially
self-consistent $GW_0$ levels. In contrast, solving the Bethe-Salpeter equation
on top of the $GW_0$ calculation yields an exciton binding energy for the
direct exciton at the $K$ point in close agreement with the DMC value. Vibrational renormalization of the electronic band gap is found to be
significant in both the monolayer and the bulk. Taking vibrational effects into
account, DMC overestimates the band gap of bulk hBN, while $GW$ theory
underestimates it.(read more)