Doping Dependence of High-Energy Spectral Weights for the high-Tc Cuprates

In this paper we present calculation of the photo- and inverse photoemission spectra, and the O 1s and Cu 2p core-level spectra for the high-T(c) materials, using a multiband Hubbard Hamiltonian. The spectra are obtained for small clusters containing two Cu atoms (Cu2O7 and Cu2O8) for the undoped, electron-doped, and hole-doped cases. In order to investigate the sensitivity of the spectra to cluster size and localized versus delocalized oxygen levels, a comparison is made with a (K-dependent) impurity approach and results from a CuO4 cluster. Special attention is paid to the doping dependence of the spectra and low-energy states and to the redistribution of spectral weights upon doping.