Ab Initio Electron-Phonon Interactions Using Atomic Orbital Wavefunctions

TL;DR

This paper introduces a new ab initio method using atomic orbital wavefunctions to compute electron-phonon interactions, offering advantages over Wannier functions especially for complex materials and high-throughput applications.

Contribution

The paper develops and benchmarks an AO-based approach for electron-phonon calculations, simplifying the process for complex materials and generalizing to other localized basis sets.

Findings

AO-based calculations agree well with DFT and Wannier function results

AOs simplify e-ph calculations in complex materials

Method is suitable for high-throughput materials discovery

Abstract

The interaction between electrons and lattice vibrations determines key physical properties of materials, including their electrical and heat transport, excited electron dynamics, phase transitions, and superconductivity. We present a new ab initio method that employs atomic orbital (AO) wavefunctions to compute the electron-phonon (e-ph) interactions in materials and interpolate the e-ph coupling matrix elements to fine Brillouin zone grids. We detail the numerical implementation of such AO-based e-ph calculations, and benchmark them against direct density functional theory calculations and Wannier function (WF) interpolation. The key advantages of AOs over WFs for e-ph calculations are outlined. Since AOs are fixed basis functions associated with the atoms, they circumvent the need to generate a material-specific localized basis set with a trial-and-error approach, as is needed in WFs. Therefore, AOs are ideal to compute e-ph interactions in chemically and structurally complex materials for which WFs are challenging to generate, and are also promising for high-throughput materials discovery. While our results focus on AOs, the formalism we present generalizes e-ph calculations to arbitrary localized basis sets, with WFs recovered as a special case.