The phase transition point is usually identified comparing the behavior of U as a function of the temperature for different values of the system size L . The transition temperature is the unique point where the different curves cross in the thermodynamic limit. This behavior is based on the fact that in the critical region, T ≈ ≈ T c , the Binder parameter behaves as U ( T , L ) = b ( ϵ ϵ L 1 / ν ν ) , where ϵ ϵ = T − − T c T .