Electron-phonon coupling in transition metals beyond Wang's approximation

The electron-phonon coupling is the primary mechanism responsible for material relaxation after ultrafast laser irradiation. However, it remains an elusive variable that is extremely challenging to extract experimentally, especially at high electron temperatures. Various previous theoretical approaches to determine electron-phonon coupling demonstrated large degree of inconsistency. In this paper, we present a first-principles framework for simulating the electron-phonon coupling parameter based on the electron-phonon spectral function, going beyond the approximation introduced by Wang et al. [Phys. Rev. B 50, 8016 (1994)]. Our simulations provide electron-temperature-dependent electron-phonon coupling values for transition metals Ru, Pd, and Au. Our findings reveal significant differences between the values obtained from the exact and approximated spectral functions, thus highlighting the limitations of Wang's approximation at elevated electron temperatures.