Recent technical developments in the EPW code*

EPW is an open-source Fortran code to study electron-phonon interactions based on density-functional perturbation theory and maximally localized Wannier functions. Since its first release in 2016 as one of the core modules of the Quantum ESPRESSO suite, EPW has been widely used to investigate a variety of phonon-mediated quantum processes in real materials.

In this talk, we outline the recent technical developments in EPW. They cover both algorithmic improvements and highly scalable optimizations. To name a few, we fully exploited crystal symmetry to reduce the number of evaluations of electron-phonon matrix elements on coarse Brillouin-zone grids and we implemented multi-level MPI parallelizations combined with OpenMP to reduce communication overhead and improve strong scaling. Taken altogether, these and further additions constitute the first steps to enable the transition of EPW to exascale computations of the electron-phonon coupling.