The extended Hubbard model in the ionic limit |
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Authors: | Email author" target="_blank">F?ManciniEmail author |
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Institution: | (1) Dipartimento di Fisica “E.R. Caianiello”, Laboratorio Regionale SuperMat, INFM Università degli Studi di Salerno, 84081 Baronissi (SA), Italy |
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Abstract: | In this paper, we study the Hubbard model with intersite Coulomb
interaction in the ionic limit (i.e. no kinetic energy). It is shown
that this model is isomorphic to the spin-1 Ising model in presence
of a crystal field and an external magnetic field. We show that for
such models it is possible to find, for any dimension, a finite
complete set of eigenoperators and eigenvalues of the Hamiltonian.
Then, the hierarchy of the equations of motion closes and analytical
expressions for the relevant Green's functions and correlation
functions can be obtained. These expressions are formal because
these functions depend on a finite set of unknown parameters, and
only a set of exact relations among the correlation functions can be
derived. In the one-dimensional case we show that by means of
algebraic constraints it is possible to obtain extra equations which
close the set and allow us to obtain a complete exact solution of
the model. The behavior of the relevant physical properties for the
1D system is reported. |
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Keywords: | |
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