mat-epw-mobility

Goal

To compute the intrinsic phonon-limited carrier mobility $\mu(T)$ of a 2D semiconductor in the Self-Energy Relaxation Time Approximation (SERTA), together with the mode-resolved electron-phonon coupling matrix elements $|g(k, q, \nu)|$, from first principles using the Quantum ESPRESSO + EPW pipeline. The route interpolates the electron-phonon vertex onto dense fine grids via maximally localized Wannier functions and applies the 2D Frohlich long-range kernel needed for polar monolayers.

Background

Carrier mobility limited by phonon scattering requires the electron-phonon matrix elements $g_{mn\nu}(k, q)$ on grids far denser than any tractable DFPT calculation. EPW solves this by computing $g$ on a coarse q-grid with DFPT, transforming to a maximally localized Wannier basis, and interpolating to fine k/q meshes. For 2D polar materials, the long-range Frohlich part of $g$ diverges as $1/q$ near the zone centre and must be treated with a 2D-truncated Coulomb kernel (lpolar, system_2d), otherwise $\mu$ collapses by a factor of ~3.