Strong-coupling expansion for the Hubbard model in arbitrary dimension using slave bosons.

A strong-coupling expansion for the antiferromagnetic phase of the Hubbard model is derived in the framework of the slave-boson mean-field approximation. The expansion can be obtained in terms of moments of the density of states of freely hopping electrons on a lattice, which in turn are obtained for hypercubic lattices in arbitrary dimension. The expansion is given for the case of half-filling and for the energy up to fifth order in the ratio of hopping integral t over on-site interaction U , but can straightforwardly be generalized to the non-half-filled case and be extended to higher orders in t/U . For the energy the expansion is found to have an accuracy of better than 1% for U/t ≥ 8. A comparison is given with an earlier perturbation expansion based on the Linear Spin Wave approximation and with a similar expansion based on the Hartree-Fock approximation. The case of an infinite number of spatial dimensions is discussed. PACS: 75.10.Lp, 02.30.Mv, 71.27.+a Short title: Strong-coupling expansion for the Hubbard model INLO-PUB 23/95; January 1996; to be published in Physical Review B. ∗e-mail address: [email protected]