arXiv:cond-mat/9712184 · Physical review. B, Condensed matter
Hubbard model on d− dimensional hypercubes: Exact solution for the two-electron case
Michel Caffarel, Rémy Mosseri
Abstract
The Hubbard model is exactly solved for two particles on $d\ensuremath{-}$dimensional hypercubes. It is shown that the spectrum can be separated into two parts: a trivial ($U$-independent) part resulting from symmetries of hypercubes and a nontrivial part expressed as a single-impurity problem on a set of finite chains of size ${d}^{\ensuremath{'}}+1$ ${(d}^{\ensuremath{'}}<~d).$ The exact expression for the one-particle Green's function is given. Finally, we discuss the extension of these results to standard hypercubic lattices with periodic boundary conditions.