Exciton-Phonon Interaction and Relaxation Times from First Principles
Abstract
Electron-phonon (-ph) interactions are key to understanding the dynamics of electrons in materials, and can be modeled accurately from first-principles. However, when electrons and holes form Coulomb-bound states (excitons), quantifying their interactions and scattering processes with phonons remains an open challenge. Here we show a rigorous approach for computing exciton-phonon (ex-ph) interactions and the associated exciton dynamical processes from first principles. Starting from the ab initio Bethe-Salpeter equation, we derive expressions for the ex-ph matrix elements and relaxation times. We apply our method to bulk hexagonal boron nitride, for which we map the ex-ph relaxation times as a function of exciton momentum and energy, analyze the temperature and phonon-mode dependence of the ex-ph scattering processes, and accurately predict the phonon-assisted photoluminescence. The approach introduced in this work is general and provides a framework for investigating exciton dynamics in a wide range of materials.
Cite
@article{arxiv.2002.08913,
title = {Exciton-Phonon Interaction and Relaxation Times from First Principles},
author = {Hsiao-Yi Chen and Davide Sangalli and Marco Bernardi},
journal= {arXiv preprint arXiv:2002.08913},
year = {2020}
}