ELECTRONIC-STRUCTURE AND FERMI-SURFACE OF THE 2-DIMENSIONAL 3-BAND HUBBARD-MODEL IN DOPED CUPRATES

The electronic structure of the high-T-c copper oxides is calculated b y means of an extended two-dimensional three-band Hubbard model in the unrestricted Hartree-Fock approximation. The influence of the couplin g parameters on the obtained bands, as well as their doping dependence are investigated especially at the Fermi surface. Results are discuss ed in the light of recent experimental data for the cuprate Fermi surf aces. A comparative analysis of these conflicting data on the basis of our results sheds some light on the interpretation of the measured ba nd structures. The direct oxygen-oxygen hopping interaction is found t o be essential in fitting experimental results, suggesting that, in th e doped regime, the oxygen band plays a key role at least in the near- Ep region. Antiferromagnetic correlations among copper atoms turn out as well to be crucial. The results agree remarkably well with previous local-density calculations and with spectroscopic measurements.