EPW: A program for calculating the electron-phonon coupling using maximally localized Wannier functions

TL;DR

EPW is a FORTRAN90 program that efficiently calculates electron-phonon interactions in periodic systems using Wannier functions, enabling accurate and fast analysis of complex materials.

Contribution

It introduces a method combining density-functional perturbation theory with Wannier functions for rapid electron-phonon coupling calculations.

Findings

Allows dense Brillouin zone sampling with high accuracy.

Enables study of large and complex systems.

Integrates with Quantum-ESPRESSO and wannier90 packages.

Abstract

EPW (Electron-Phonon coupling using Wannier functions) is a program written in FORTRAN90 for calculating the electron-phonon coupling in periodic systems using density-functional perturbation theory and maximally-localized Wannier functions. EPW can calculate electron-phonon interaction self-energies, electron-phonon spectral functions, and total as well as mode-resolved electron-phonon coupling strengths. The calculation of the electron-phonon coupling requires a very accurate sampling of electron-phonon scattering processes throughout the Brillouin zone, hence reliable calculations can be prohibitively time-consuming. EPW combines the Kohn-Sham electronic eigenstates and the vibrational eigenmodes provided by the Quantum-ESPRESSO package [1] with the maximally localized Wannier functions provided by the wannier90 package [2] in order to generate electron-phonon matrix elements on arbitrarily dense Brillouin zone grids using a generalized Fourier interpolation. This feature of EPW leads to fast and accurate calculations of the electron-phonon coupling, and enables the study of the electron-phonon coupling in large and complex systems.