The one-band Hubbard model is considered in the slave-boson formulation first introduced by Kotliar and Ruckenstein. It is shown that a mean-field approximation, where broken-symmetry states appropriate for a bipartite lattice are allowed, leads to a quantitative agreement with quantum Monte Carlo results for local observables over a wide range of interactions (0<U≤20t) and doping (0<〈n〉≤1). Thus, our saddle-point solutions constitute an excellent starting point for a systematic treatment of fluctuations.

• Received 2 July 1990

DOI:https://doi.org/10.1103/PhysRevLett.65.1379