THE ADIABATIC CONNECTION BETWEEN THE RESONATING-VALENCE-BOND STATE AND THE GROUND-STATE OF THE HALF-FILLED PERIODIC ANDERSON MODEL

A one-parameter family of models interpolates between the periodic And erson model with infinite repulsion at half-filling and a model whose ground state is exactly the resonating-valence-bond state. It is shown numerically that the excitation gap does not collapse. Therefore the ground states of the two models are adiabatically connected.