title: Duality and Fisher zeros in the two-dimensional Potts model on a square lattice.
abstract: A phenomenological approach to the ferromagnetic two-dimensional (2D) Potts model on square lattice is proposed. Our goal is to present a simple functional form that obeys the known properties possessed by the free energy of the q-state Potts model. The duality symmetry of the 2D Potts model together with the known results on its critical exponent α allows us to fix consistently the details of the proposed expression for the free energy. The agreement of the analytic ansatz with numerical data in the q=3 case is very good at high and low temperatures as well as at the critical point. It is shown that the q>4 cases naturally fit into the same scheme and that one should also expect a good agreement with numerical data. The limiting q=4 case is shortly discussed.
authors.affiliation: Instituto de Física, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile. marco.astorino@gmail.com
authors.forename: Marco
authors.initials: M
authors.lastname: Astorino
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Canfora