A Class of Variational Singlet Wave Functions for the Hubbard Model Away From Half-filling.

We present a class of variational wavefunctions for strong coupling Heinsenberg Hubbard models. These are written in the form of three factors - a pair of determinants and Jastrow function, and are made out of orbitals -a-la Hartee Fock - which solve a fictitious one body problem. The wavefunctions respect various constraints known from general principles and appear to be potentially useful in understanding the possible behaviour of the models in quantitative terms.