ON THE GROUND-STATE STRUCTURE OF THE 2-DIMENSIONAL HUBBARD-MODEL ON A SQUARE LATTICE - QUANTUM MELTING OF THE NEEL ORDERING

A two-dimensional t-J model equivalent at t >> J to the Hubbard model is considered by a variational method. We suggest the compact ansatz for the mobile hole wave function. The dispersion of this hole on the Neel and RVB background is calculated. It is shown that the doping induces a transition from the Neel state to the spin-liquid RVB state. At 1 less-than-or-equal-to t/J less-than-or-equal-to 4 the transition point is at the hole concentration x approximately 0.1.