Abstract
We discuss the two-sublattice Hubbard model using a new Green's-function technique proposed by Sawada. It is found that the initial two bands split into four because of the interaction. The perturbed density of states is seen to be obtainable from the unperturbed case by a simple transformation, the "shape-factor" modulating the shape of the bands being different from unity only in the magnetic state. It is seen that in the atomic limit the results agree with the exact calculation, and in the limit of weak coupling one gets back the earlier known results.

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