Probing the LDA-1/2 method as a starting point for $G_0W_0$ calculations

TL;DR

This paper evaluates the LDA-1/2 method as a computationally efficient starting point for $G_0W_0$ calculations, showing it improves band gap predictions over LDA and PBE0 in various materials.

Contribution

It systematically compares LDA-1/2 with LDA and PBE0 as starting points for $G_0W_0$, demonstrating its effectiveness in reducing band gap errors.

Findings

LDA-1/2 reduces mean absolute error of band gaps by 50%

LDA-1/2 performs well across diverse solids

It offers a computationally efficient alternative to hybrid functionals

Abstract

Employing the $G_0W_0$ approximation of Hedin's $GW$ approach one can obtain quasi-particle energies of extended systems and molecules with good accuracy. However, for many materials, semi-local exchange-correlation functionals are unsatisfactory starting points for $G_0W_0$ calculations. Hybrid functionals often improve upon them, but at a substantially higher computational cost. As an alternative, we suggest the LDA-1/2 method, which provides reasonable band gaps, without being computationally involved. In this work, we systematically compare 3 starting points for $G_0W_0$: LDA, PBE0, and LDA-1/2. A selection of solids is chosen for this benchmark: C, Si, SiC, AlP, LiF, MgO, Ne, Ar, GaN, GaAs, CdS, ZnS, and ZnO. We demonstrate that LDA-1/2 is a good starting point in most cases, reducing the mean absolute error of band gaps by 50% when compared to the other 2 functionals.