Abstract
The canonical Monte Carlo method is used to study the order-disorder phase transition of the Falicov-Kimball model away from half-filling. It is shown that the transition from various inhomogeneous ground-state phases to the disordered phase can be either direct or indirect.
The indirect transition means that the ground-state phase first, at critical temperature tau(c), changes to a different ordered phase and at the temperature, that can be several times higher than tau(c), finally changes to the disordered phase. It is shown that the Falicov-Kimball model, depending on the ground state phase, undergoes first order or second order phase transition or can even undergo both for the same parameters and different temperatures if the transition from the ground-state phase to the disordered phase is indirect.