Phonons and superconducting p-state pairing in Pd

We present an analytical calculation of the electron-phonon parameters for s- and p-state pairing in Pd, lambda0/sup ph/, and lambda1/sup ph/. The calculation is based on Doniach's six half-sphere Fermi-surface model for the heavy d electrons, a Debye and an Einstein model for intra- and intersphere phonon-scattering processes, respectively, and the LCMTO (linear combination of muffin-tin orbitals) representation to obtain the electron-phonon matrix elements. The group-theoretical method of Allen is employed in solving the anisotropic gap equation at the multiply sheeted Fermi surface for s- and p-state pairing interactions. The phonon-mediated interaction, I/sup ph/(k,k'), is attractive for all momentum transfers, k-k', and yields the BCS parameter, lambda0/sup ph/=0.153, in agreement with Papaconstantopoulos et al. Our result for p-state pairing is lambda/sup ph/1=0, when the Einstein phonon model is used for both intra- and intersheet scattering processes and lambda1/sup ph/=0.089 lambda0/sup ph/ when the Debye model is applied to the small-momentum intrasheet transitions of the Cooper pairs. The weakness of the p-state interaction is due to the cancellation between the contributions from intrasheet scattering and from large-momentum intersheet scattering processes. A detailed discussion of the results is presented in terms of the parameters of our electron-phonon model