Calculated electron-phonon contributions to phonon linewidths and to the electronic mass enhancement in Pd

Abstract

This paper presents a calculation of the linewidths of phonons in Pd owing to decay into electron-hole pairs. Korringa-Kohn-Rostoker energies and wave functions are used with the rigid-muffin-tin approximation (for the electron-phonon matrix element). The linewidths of the longitudinal $[\ensuremath{\zeta}00]$ phonons show a sharp maximum which is in qualitative agreement with the recent experimental observations of Youngblood et al. Relatively large linewidths are calculated for a transverse mode (${T}_{1}$) along the [110] direction, which are in good agreement with the previous experiment of Miiller. Both the matrix element and the joint density of states at the Fermi energy contribute to the magnitude of the calculated linewidths. The electron-phonon contribution to the electronic mass enhancement is calculated to be 0.41. This result is used to estimate the contribution due to paramagnetic fluctuations.