An alternative order parameter for the 4-state Potts model.

We have investigated the dynamic critical behavior of the two-dimensional 4-state Potts model using an alternative order parameter first used by Vanderzande [J. Phys. A 20 (1987) L549] in the study of the Z(5) model. We have estimated the global persistence exponent ?g by following the time evolution of the probability P(t) that the considered order parameter does not change its sign up to time t. We have also obtained the critical exponents ?, z, ?, and ? using this alternative definition of the order parameter and our results are in complete agreement with available values found in literature