First-principles study of excitons in the optical spectra of silver chloride

TL;DR

This study uses advanced first-principles methods to analyze excitonic effects in silver chloride's optical spectra, revealing the importance of many-body interactions and exciton localization.

Contribution

It provides the first comprehensive theoretical analysis of excitons in AgCl using GW and Bethe-Salpeter methods, with a novel model screening approach.

Findings

Strong excitonic effects in AgCl optical spectra

Accurate exciton characterization requires Bethe-Salpeter equation

Localization differences between bright and dark excitons

Abstract

Silver chloride is a material that has been investigated and used for many decades. Of particular interest are its optical properties, but only few fundamental theoretical studies exist. We present first-principles results for the optical properties of AgCl, obtained using time-dependent density functional theory and many-body perturbation theory. We show that optical properties exhibit strong excitonic effects, which are correctly captured only by solving the Bethe-Salpeter equation starting from quasiparticle self-consistent GW results. Numerical simulations are made feasible by using a model screening for the electron-hole interaction in a way that avoids the calculation of the static dielectric constant. A thorough analysis permits us to discuss localization in bright and dark excitons of silver chloride.