Effect of Semicore Orbitals on the Electronic Band Gaps of Si, Ge, and GaAs within the GW Approximation

TL;DR

This study investigates how semicore states influence the electronic band gaps of Si, Ge, and GaAs using GW calculations with ab initio pseudopotentials, showing that semicore effects can be effectively captured within standard valence-only approaches.

Contribution

It demonstrates that semicore states' effects on band gaps are accurately described using valence-only pseudopotentials within the GW framework, challenging recent claims.

Findings

Semicore states have a significant impact on band gaps.

Standard valence-only pseudopotentials can account for semicore effects.

Results agree with experimental measurements.

Abstract

We study the effect of semicore states on the self-energy corrections and electronic energy gaps of silicon, germanium and GaAs. Self-energy effects are computed within the GW approach, and electronic states are expanded in a plane-wave basis. For these materials, we generate {\it ab initio} pseudopotentials treating as valence states the outermost two shells of atomic orbitals, rather than only the outermost valence shell as in traditional pseudopotential calculations. The resulting direct and indirect energy gaps are compared with experimental measurements and with previous calculations based on pseudopotential and ``all-electron'' approaches. Our results show that, contrary to recent claims, self-energy effects due to semicore states on the band gaps can be well accounted for in the standard valence-only pseudopotential formalism.