First- and second-neighbor square-lattice Potts model: Renormalization-group treatment

Within a real-space renormalization-group framework, we study the q-state Potts model in a square lattice, assuming a positive second-neighbor coupling constant and an arbitrary sign for the first-neighbor coupling constant. The q evolution of the full phase diagram as well as the thermal and magnetic critical exponents are obtained. Whenever comparison with available results is possible, the agreement is either exact or very satisfactory.