GROUND STATE OF CORRELATED ELECTRONS IN A NARROW ALMOST HALF-FILLED s BAND

We consider a system of conduction electrons in an almost half-filled s band with an infinitely strong delta-function type repulsive potential, and with non-vanishing transfer matrix elements only between nearest neighbors. We find rigorously that the totally polarized ferromagnetic state is the ground state for sc and bcc and for fcc and hcp with N(e) > N, N(e) and N being respectively the number of electrons and atoms, and that it is not the ground state for fcc and hcp with N(e) < N.