A simple screened exact-exchange approach for excitonic properties in solids

TL;DR

The paper introduces a computationally efficient screened exact-exchange (SXX) method for accurately calculating optical properties and excitonic effects in solids, simplifying the Bethe-Salpeter equation approach.

Contribution

It proposes a new SXX method that simplifies excitonic calculations in solids, bridging BSE and hybrid functional approaches with lower computational cost.

Findings

SXX accurately predicts bound excitons and spectra in semiconductors and insulators.

SXX has significantly lower computational cost than BSE.

SXX performs well across different material types.

Abstract

We present a screened exact-exchange (SXX) method for the efficient and accurate calculation of the optical properties of solids, where the screening is achieved through the zero-wavevector limit of the inverse dielectric function. The SXX approach can be viewed as a simplification of the Bethe-Salpeter equation (BSE) or, in the context of time-dependent density-functional theory, as a first step towards a new class of hybrid functionals for the optical properties of solids. SXX performs well for bound excitons and continuum spectra in both small-gap semiconductors and large-gap insulators, with a computational cost much lower than that of the BSE.