Anisotropy of the Electron-Phonon Interaction in Copper

Absolute values of the anisotropy of the electron-phonon renormalization and of the anisotropy of the temperature-dependent ($T^3$) component of the quasiparticle scattering rate on the Fermi surface of copper have been calculated. The electron-phonon matrix element is expressed in terms of an augmented-plane-wave (APW) phase-shift pseudopotential. The anisotropies of the Fermi surface, the phonon spectrum, and the wave functions of the initial and final states are explicitly taken into account. The results are compared with experimental data on the scattering rate of quasiparticles by thermal phonons in copper. The calculation predicts an anisotropic variation of the absolute scattering rate which is in good over-all agreement with the experimental data. It is found that the large increase on the scattering rate on the necks can be explained by taking into account the scattering of electrons by transverse phonons. The predicted anisotropy of the renormalization factor is in good agreement with that obtained from a phenomenological interpretation of experimental cyclotron-mass data. The results of this paper suggest the applicability of the APW pseudopotential to the description of the electron-phonon interaction in other metals of the transition series.