EPW is an open-source F90/MPI code which calculates properties related to the electron-phonon interaction using 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 method employed by the code. The development of EPW is led by Sabyasachi Tiwari, Samuel Poncé, Emmanouil Kioupakis, Roxana Margine, and Feliciano Giustino.
The most recent reference technical manuscript is:
H. 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 distributed as part of the Quantum ESPRESSO materials simulation suite.
The code was written by Feliciano Giustino (EPW v1) while in the Cohen/Louie group at the University of California, Berkeley. Jesse Noffsinger (Berkeley) performed the integration with Quatum ESPRESSO (EPW v2). Brad Malone (Harvard) and Cheol-Hwan Park (Seoul National University) contributed with tests and benchmarks. 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 Froehlich 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). He also 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). Sabyasachi Tiwari (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 development of EPW is led and coordinated by Sabyasachi Tiwari, Samuel Poncé, Emmanouil Kioupakis, Roxana Margine, and Feliciano Giustino. The EPW Collaboration includes (in alphabetic order): Kyle Bushick, Feliciano Giustino, Viet-Anh Ha, Samad Hajinazar, Emmanouil Kioupakis, Jon Lafuente-Bartolomé, Hyungjun Lee, Johsua Leveillee, Chao Lian, Jae-Mo Lihm, Francesco Macheda, Roxana Margine, Hitoshi Mori, Hari Paudyal, Samuel Poncé, Weng-Hong Sio, Sabyasachi Tiwari, Marios Zacharias, Xiao Zhang.
EPW is developed under git within the GitLab portal.
As of September 2023, EPW consists of 76,057 Fortran lines (including comments).
Computing electron-phonon properties with 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