About

EPW is an open-source F90/MPI/OpenMP/OpenACC software project for first-principles calculations of electron-phonon interactions and related materials properties. The code employs Density-functional perturbation theory and Maximally localized Wannier functions. The name is derived from the words “Electron-phonon Wannier” which refer to the Wannier-Fourier interpolation of the electron-phonon matrix elements employed by the code. The name of the code is “EPW” (not “Electron-phonon Wannier”). Since v5.3.1, the EPW project includes the ZG code for calculating electron-phonon couplings using supercells and the special displacement method, and the extension of this method to anharmonic systems.

The EPW project is led by its steering committee, which consists of Sabyasachi Tiwari, Samuel Poncé, Emmanouil Kioupakis, Roxana Margine, and Feliciano Giustino.

The most recent reference technical manuscript is:

  1. Lee, S. Poncé, K. Bushick, S. Hajinazar, J. Lafuente-Bartolome, J. Leveillee, C. Lian, J.-M. Lihm, F. Macheda, H. Mori, H. Paudyal, W. H. Sio, S. Tiwari, M. Zacharias, X. Zhang, N. Bonini, E. Kioupakis, E. R. Margine, and F. Giustino, Electron–phonon physics from first principles using the EPW code, npj Comput. Mater. 9, 156 (2023).

EPW is an independent code that participates in and is distributed with the Quantum ESPRESSO materials simulation suite, in collaboration with the Quantum ESPRESSO Foundation.

History

The code was written by Feliciano Giustino (EPW v1) while in the Cohen/Louie group at the University of California, Berkeley. Jesse Noffsinger performed the integration with Quantum ESPRESSO (EPW v2). Brad Malone and Cheol-Hwan Park contributed with tests and benchmarks to EPW v2. Roxana Margine implemented the anisotropic Eliashberg theory while in the Giustino group at the University of Oxford (EPW v3). Carla Verdi developed the electron-phonon interpolation for polar materials including Fröhlich correction while in the Giustino group at Oxford. Samuel Poncé made the code compatible with Quantum ESPRESSO v5, optimized it, and developed an automatic test farm for the code (EPW v4). Samuel Poncé implemented the electronic transport module while in the Giustino group at the University of Oxford (EPW v5). Hyungjun Lee coordinated code development in the Giustino group at the University of Texas at Austin (2019-2023). Emmanouil Kioupakis and Xiao Zhang contributed the indirect optical absoprtion module (EPW v5). Weng-Hong Sio, Chao Lian, and Jon Lafiente-Bartolomé developed the polaron module at Oxford and at UT Austin (EPW v5). Samuel Poncé introduced support for quadrupoles (EPW v5). Sabyasachi Tiwari developed the quasidegenerate perturbation theory module and introduced image parallelism; Wooil Yang introduced support for Hubbard-corrected DFPT+U (EPW v6). Tae Yun Kim (UT Austin) developed the GPU accelerated version of the code (EPW v6.1). Marios Zacharias developed the ZG code for special displacements. Sabyasachi Tiwari at UT Austin is the current project coordinator.

EPW is based on the method introduced in F. Giustino et al, Phys. Rev. B 76, 165108 (2007). An extended description of the most recent public release has been published in H. Lee al, npj Comput. Mater. 9, 156 (2023).

The EPW Collaboration

As of March 2026, the EPW Collaboration includes (in alphabetic order):

Álvaro Carrasco-Álvarez, Kyle Bushick, Fabio Caruso, Jie-Cheng Chen, Zhenbang Dai, Adam Denchfield, Nina Girotto, Feliciano Giustino, Viet-Anh Ha, Emmanouil Kioupakis, Jon Lafuente-Bartolomé, Kaifa Luo, Tae Yun Kim, Jae-Mo Lihm, Zhe Liu, Roxana Margine, Hitoshi Mori, Yiming Pan, Samuel Poncé, Danylo Radevych, Young-Woo Son, Sabyasachi Tiwari, Shashi Mishra, Amanda Wang, Wooil Yang, Marios Zacharias, Xiao Zhang.

EPW is developed under git within the EPW GitLab portal.

As of March 2026, EPW consists of 104,251 lines of code (including comments).

What can be computed using EPW

EPW can be used to compute:

  • The total electron-phonon coupling strenght

  • The anisotropic Eliashberg spectral function

  • The transport spectral function

  • The anisotropic superconducting gap within the Eliashberg theory

  • The electron and phonon self-energies arising from the electron-phonon interaction

  • The phonon linewidths and lifetimes arising from the electron-phonon interaction

  • The electron linewidths and lifetimes arising from the electron-phonon interaction

  • The temperature-dependence of the carrier lifetimes

  • The spectral functions needed for the calculation of ARPES spectra

  • The temperature-dependent electron and hole mobility within the Boltzmann transport formalism

  • Magnetortransport coefficients such as the Hall mobility

  • Small and large polarons

  • Indirect phonon-assisted optical absorption

  • Temperature-dependent properties using the special displacement method

  • Direct plus indirect phonon-assisted absorption within quasidegenerate perturbation theory