PHOTOEMISSION SPECTRA OF CORRELATED ELECTRON-SYSTEMS

The joint valence band photoemission spectrum and BIS of an N fold degenerate Hubbard model is calculated using a 1/N expansion, that retains the coherence of the lattice. The lowest order term in the expansion constitutes a Hartree-Fock mean field theory, and to next leading order one finds that the dynamics are dominated by boson like collective excitations. The one electron spectra are, generally, found to have long tails, however in the vicinity of the Fermi-level the spectra shows narrow features. The appearance of satellites and large mass enhancements are correlated with the softening of the boson modes. © 1990.