The standard Potts model is investigated in the framework of nonextensive statistical mechanics. We performed Monte Carlo simulations on two-dimensional lattices with linear sizes ranging from 16 to 64 using the Metropolis algorithm, where the classical Boltzmann–Gibbs transition probabilities...

The general conditions for the existence of a negative heat capacity branch in nonextensive finite systems are reviewed. Partial energy fluctuations are proposed as a directly measurable observable of such a phenomenon in Gibbs as well as Tsallis equilibria.

The specific Gibbs free energy has been calculated for the infinite range Ising model with fixed and finite interaction strength. The model shows a temperature driven first-order phase transition that differs from the infinite ranged Ising model with weak coupling. In the temperature-field phase...