COMPOSITE-FERMION THEORY FOR THE STRONGLY CORRELATED HUBBARD-MODEL

We study a class of variational wave functions for strongly correlated systems by expanding the electron operators as composites of spin-1/2 Fermi fields and spinless Fermi fields. The composite particles automatically satisfy the local constraint of no double occupancy and include correlations between opposite-spin particles in a very physical way. We calculate the energy and correlation functions for the one-dimensional U = infinity Hubbard model, where a comparison with exact results is made. The method is computationally very tractable and can readily be generalized to higher dimensions.