Carrier mobilities and electron-phonon interactions beyond DFT

TL;DR

This paper presents a versatile finite-difference method for calculating electron-phonon interactions using advanced electronic structure techniques beyond standard DFT, improving accuracy in predicting carrier mobilities and effective masses.

Contribution

The authors develop a new projectability scheme and computational framework that integrates with existing codes to efficiently compute electron-phonon couplings for various many-body methods.

Findings

Advanced functionals predict different electron-phonon couplings.

Modified band curvatures lead to more accurate mobility estimates.

Method is applicable to complex materials like silicon and gallium arsenide.

Abstract

Electron-phonon coupling is a key interaction that governs diverse physical processes such as carrier transport, superconductivity, and optical absorption. Calculating such interactions from first-principles with methods beyond density-functional theory remains a challenge. We introduce here a finite-difference framework for computing electron-phonon couplings for any electronic structure method that provides eigenvalues and eigenvectors, and showcase applications for hybrid and Koopmans functionals, and $GW$ many-body perturbation theory. Our approach introduces a novel projectability scheme based on eigenvalue differences and bypasses many of the limitations of the direct finite difference methods. It also leverages symmetries to reduce the number of independent atomic displacements, thereby keeping computational costs manageable. This approach enables seamless integration with established first-principles codes for generating displaced supercells, performing Wannier interpolations, and evaluating transport properties. Applications to silicon and gallium arsenide show that advanced electronic-structure functionals predict different electron-phonon couplings and modify band curvatures, resulting in much more accurate estimates of intrinsic carrier drift mobilities and effective masses. In general, our method provides a robust and accessible framework for exploring electron-phonon interactions in complex materials with state-of-the-art electronic structure methods.