AN EXPERIMENTAL AND THEORETICAL-STUDY OF THE PHOTOEMISSION FROM NI(110)

We have investigated the electronic structure of the d bands in Ni along the GAMMA(SIGMA)K(S)X direction using a combination of angle-resolved UV photoemission measurements and photocurrent calculations including correlation effects. In the calculations we used a potential for the excited state that included self-energy corrections based on the model of Treglia et al. The calculations reproduce all of the main features in the experimental spectra. In particular, there is good agreement with the observed dispersion of the quasiparticle states of SIGMA-3(S3) and SIGMA-4(S4) symmetry. The calculations indicate that the correlations produce a marked energy dependence of the exchange splitting, in contrast to the essentially rigid shift obtained in standard one-electron calculations, and the results for the SIGMA-4-up-or-down states are in very good argreement with photoemission measurements along KX.