Insulator-metal transitions in the Falicov-Kimball model with a generalized type of hopping

The possibilities for the insulator-metal transitions in the spinless Falicov-Kimball model with a generalized type of hopping are studied using small-cluster exact diagonalization calculations. it is shown that for small values of the interaction strength U the energy gap Delta vanishes discontinuously at some critical value of the f-electron occupation number and thus in the pressure-induced case the model can describe the insulator-metal transition observed in some rare-earth compounds.