Phase Transition in the Three-State Potts-Kihara Model

The symmetry breaking potential method is applied to investigate the phase transition in the three-state Potts-Kihara model on f. c. c. lattice. Due to the cubic term of the order parameter appearing in the Landau expansion of the thermodynamical potential, the transition seems necessarily to be of first order in practical approximate calculations. However, by investigating some relevant quantities such as induced transition and spinodal temperatures up to the eighth approximation in a high temperature expansion, it is shown that the phase transition is very likely of second order.