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 meannumber of trapped electrons in an impurity in a semiconductor where the doubleoccupancy of the impurity is forbidden and similar to the distribution functionof the usual fermions. In one dimension, the thermodynamics of freeorthofermions gives the known exact results of the infinite U Hubbard model.Thus it shows that at least in one dimension the fermions with exclusion ofdouble occupancy of sites behave as free orthofermions. Since freeorthofermions Hamiltonian is exactly soluble in any dimension, it can beemployed to ascertain the accuracy of the approximate solutions of the Hubbardmodel, frequently used for the strongly correlated electron systems like hightemperature superconductors.
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