Single-band effective Hamiltonian for high Tc-superconductors from a cluster analysis of experimental data

We use a CuO6 cluster with all Cu 3d and O 2p levels to describe the electronic properties of Cu-oxide superconductors. On the basis of band structure calculations and photoemission data we estimate the key parameters: Cu-O and O-O hopping integrals, on-site atomic energies, and Coulomb repulsion between Cu 3d-levels. The ground-state of two holes on this cluster is shown to be a strongly bound singlet, which allows one to derive a single band effective hamiltonian for the CuO2 layers of Cu-oxide superconductors.link_to_subscribed_fulltex