ONE-PARTICLE EXCITATION-SPECTRA OF HUBBARD SYSTEMS WITH INTERSITE INTERACTIONS

Using exact diagonalization techniques, the photoemission and inverse photoemission spectra of an extended Hubbard model with intersite inte ractions are calculated, The intersite interaction is found to suppres s the spectral features driven by the on-site interaction, leading to a spectral narrowing and anomalous behavior in the spin polarization o f the spectra and in the doping dependence of the low-energy spectral weight. General implications of the calculated results are discussed.