2021/05/20 by Fulvio Paleari, Paleari, Fulvio, Andrea Marini +1 · 1 citation
Engineering · Materials Science · #FOS: Physical sciences #Machine Learning in Materials Science #Materials Science (cond-mat.mtrl-sci) #Other Condensed Matter (cond-mat.other) #Semiconductor materials and devices #Thermal properties of materials
paper · pdf · doi:10.48550/arxiv.2105.09828
openalex publication_date 2021/05/20 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
State-of-the-art approaches to calculate the electron-phonon and the phonon-electron self-energy are based on a mean-field approximation for the interacting electronic system. This approach introduces an overscreening error which results in an underestimation of the electron-phonon coupling strength. We introduce a theoretical and numerical approach for the calculation of the phonon-electron self-energy without the overscreening error. Starting from the out-of-equilibrium Kadanoff-Baym equations for the phonon propagator, we discuss and compare the overscreened (i.e., symmetrically screened) and overscreening--free (i.e., asymmetrically screened) cases. We point out that the difficulty in treating the latter stems from the static approximation to the dielectric function and from the need to obtain a self-energy that preserves the elementary scattering processes. We solve both problems in the equilibrium case by considering a manifestly symmetric form of the correct self-energy which can be easily calculated numerically and yields an overscreening--free coupling strength. Finally, we describe the numerical implementation of this treatment into the first--principles Yambo code for the calculations of phonon linewidths.