EPW: Electron–phonon coupling, transport and superconducting properties using maximally localized Wannier functions

Abstract

The EPW (Electron-Phonon coupling using Wannier functions) software is a Fortran90 code that uses density-functional perturbation theory and maximally localized Wannier functions for computing electron–phonon couplings and related properties in solids accurately and efficiently. The EPW v4 program can be used to compute electron and phonon self-energies, linewidths, electron–phonon scattering rates, electron–phonon coupling strengths, transport spectral functions, electronic velocities, resistivity, anisotropic superconducting gaps and spectral functions within the Migdal–Eliashberg theory. The code now supports spin–orbit coupling, time-reversal symmetry in non-centrosymmetric crystals, polar materials, and k and q-point parallelization. Considerable effort was dedicated to optimization and parallelization, achieving almost a ten times speedup with respect to previous releases. A computer test farm was implemented to ensure stability and portability of the code on the most popular compilers and architectures. Since April 2016, version 4 of the EPW code is fully integrated in and distributed with the Quantum ESPRESSO package, and can be downloaded through QE-forge at http://qe-forge.org/gf/project/q-e. Program summaryProgram title: EPWCatalogue identifier: AEHA_v2_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEHA_v2_0.htmlProgram obtainable from: CPC Program Library, Queen’s University, Belfast, N. IrelandLicensing provisions: GNU General Public Licence 3No. of lines in distributed program, including test data, etc.: 1635099No. of bytes in distributed program, including test data, etc.: 22533187Distribution format: tar.gzProgramming language: Fortran 90, MPI.Computer: Non-specific.Operating system: Unix/Linux.RAM: Typically 2GB/coreClassification: 7.3, 7.8, 7.9.External routines: LAPACK, BLAS, MPI, FFTW, Quantum- ESPRESSO package [1]Does the new version supersede the previous version?: YesNature of problem:Calculation of electron and phonon self-energies, linewidths, electron–phonon scattering rates, electron–phonon coupling strengths, transport spectral functions, electronic velocities, resistivity, anisotropic superconducting gaps and spectral functions within the Migdal–Eliashberg theory.Solution method:The code relies on density-functional perturbation theory and maximally localized Wannier functions.Reasons for new version:New features (listed in the paper) and optimization of the code.Summary of revisions:Recent developments and new functionalities are described in Section 2 of the paper.Running time:Up to several hours on several tens of processors.