Thermodynamics of infinite U Hubbard model

TL;DR

This paper demonstrates that the infinite U Hubbard model in one dimension can be exactly solved by mapping it to a free orthofermion system, providing insights into strongly correlated electron systems.

Contribution

It establishes the equivalence of the infinite U Hubbard model to a free orthofermion Hamiltonian, enabling exact solutions in any dimension.

Findings

Exact thermodynamics in 1D matches known results.

Free orthofermions behave like electrons with double occupancy exclusion.

Provides a new approach to approximate solutions in higher dimensions.

Abstract

The infinite U Hubbard model, with exclusion of double occupancy of sites, can be considered as a free orthofermion Hamiltonian which is exactly soluble. It is found that the orthofermion distribution function is similar to the mean number of trapped electrons in an impurity in a semiconductor where the double occupancy of the impurity is forbidden and similar to the distribution function of the usual fermions. In one dimension, the thermodynamics of free orthofermions gives the known exact results of the infinite U Hubbard model. Thus it shows that at least in one dimension the fermions with exclusion of double occupancy of sites behave as free orthofermions. Since free orthofermions Hamiltonian is exactly soluble in any dimension, it can be employed to ascertain the accuracy of the approximate solutions of the Hubbard model, frequently used for the strongly correlated electron systems like high temperature superconductors.