Parameters of a Hubbard Hamiltonian to describe superconducting Cu oxides

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Abstract
The parameters of a Hubbard Hamiltonian to describe superconducting Cu oxides are derived on the basis of (i) band-structure calculations for the hopping integrals through a tight-binding fit; (ii) photoemission and optical absorption for on-site energies and Coulomb repulsion within a cluster analysis of the experimental data. The undoped material described by this Hamiltonian is a Mott insulator; its antiferromagnetism can be accounted for by superexchange theory. An extra hole localized around a Cu atom is shown to form a singlet with the hole already present in the undoped material. It is argued that this local singlet is a good starting point to describe the holes created in the Cu oxide layers upon doping.