Extended Hubbard Model in the Dimer Representation. II. Lattice Hamiltonian in the Large U Limit

B. Grabiec and M. Matlak Institute of Physics, Silesian University, Uniwersytecka 4, 40-007 Katowice, Poland

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Received: December 14, 2001

Using the exact decomposition of the sc lattice into a set of interacting dimers (each dimer is described by the extended Hubbard Hamiltonian) and exact solution of the dimer problem (preceding paper) we exactly find the form of the extended Hubbard model in the case of a crystal in the large U limit. We apply a new, nonperturbative approach based on the exact projection procedure onto a dimer subspace occupied by electrons in this limit (it is the only assumption). The resulting Hamiltonian is very complicated and contains a variety of multiple magnetic and nonmagnetic interactions deeply hidden in its original form (site representation). We also present a simplified version of the model to better visualize a mixture of different interactions resulting from this approach.

DOI: 10.12693/APhysPolA.101.549 PACS numbers: 71.10.-w, 71.10.Ca, 71.10.Fd