Self-energy contributions to the electronic structure of Ni

We have calculated the band- and wave-vector-dependent second-order self-energies for several states in ferromagnetic nickel based upon a parametrization we have previously made of Wang and Callaway's energy bands. The spectral densities obtained from these self-energies show, in agreement with experiment, that the exchange splitting is reduced and that bands near the Fermi energy are flattened relative to the one-electron bands. The spectral densities at the bottom of the $d$ bands are much broadened, but show very little shift relative to the one-electron energies. This is in agreement with the photoemission data of Lapeyre et al. but in disagreement with the conflicting data of Eastman et al. and Eberhardt and Plummer.