Two-band Hamiltonian forCuO2planes

Abstract
We show that the three-band Hubbard model of CuO2 planes, with Cu and bonding O states, can be reduced to a two-band model when the large O-O hopping is taken into account. This leads to an Anderson-lattice-type model with large Coulomb interaction on Cu sites, if the smaller interactions on O sites are neglected. The reduction of the Hilbert space leads to longer-range terms in the two-band Hamiltonian, which we describe by an explicit set of hopping parameters to third neighbor.