Electron–phonon contribution to the phonon and excited electron (hole) linewidths in bulk Pd

We present an ab initio study of the electron–phonon (e–ph) coupling and its contribution to the phonon linewidths and to the lifetime broadening of excited electron and hole states in bulk Pd. The calculations, based on density-functional theory, were carried out using a linear-response approach in the plane-wave pseudopotential representation. The obtained results for the Eliashberg spectral function α²F(ω), e–ph coupling constant λ, and the contribution to the lifetime broadening, Γ_e−ph, show strong dependence on both the energy and momentum of an electron (hole) state. The calculation of phonon linewidths gives, in agreement with experimental observations, an anomalously large broadening for the transverse phonon mode T₁ in the Σ direction. In addition, this mode is found to contribute most strongly to the electron–phonon scattering processes on the Fermi surface.