SINGLE-HOLE STATE IN HALF-FILLED 2D HUBBARD-MODEL

We have investigated the ground state of a single hole in the half-filled Hubbard model in a 2D square lattice using the coupled-cluster method. In particular we obtained an analytical expression of the hole energy dispersion function epsilon-(k) which is consistent with earlier studies on the t-J model in the strong-coupling limit. An appreciable discrepancy on the hole energy bandwidth is, however, observed between the Hubbard model and the t-J model. We believe that this discrepancy is due to the absence of the three-site interaction term in the t-J model.