The electronic structure of $\beta$-HgS via $GW$ calculations

TL;DR

This paper uses advanced relativistic $GW$ calculations to clarify the electronic structure of $eta$-HgS, resolving discrepancies in previous theoretical predictions and providing results consistent with experimental data.

Contribution

It demonstrates that fully-relativistic $GW$ calculations agree with $GW$+SOC results, clarifying the topological nature and electronic properties of $eta$-HgS.

Findings

Band gap of 0.10 eV consistent with experiments

Electron effective mass of 0.07 $m_e$ matches observed data

Band ordering aligns with $GW$+SOC predictions

Abstract

The electronic structure of the zincblende $\beta$-HgS is not well understood. Previous first-principles calculations using fully-relativistic density functional theory and many-body perturbation theory in the fully-relativistic $GW$ approach have predicted an inverted, topologically non-trivial ordering of these states, with the $s$-like $\Gamma_6$ state occupied. However, other calculations using the $GW$ approach in which spin-orbit coupling is added perturbatively ("$GW$+SOC") predict the $p$-$d$ hybridized $\Gamma_7$ and $\Gamma_8$ states to be occupied and the $\Gamma_6$ state to be unoccupied, suggesting that $\beta$-HgS is a topologically trivial small band gap semiconductor. In the present work, a plane-wave pseudopotential fully-relativistic $GW$ calculation finds a band ordering in agreement with the previous $GW$+SOC calculations. The calculated band gap is 0.10 eV and the electron effective mass is 0.07 $m_e$, in good agreement with experiment.