Phase transitions in the two-dimensional slightly diluted five-vertex Potts model

Phase transitions in the two-dimensional slightly diluted Potts model on a square lattice at $q$ = 5 have been studied using the computer simulation method. The systems with linear sizes $L\times L = N$, $L$ = 10 – 120 are considered. It is shown based on the forth-order Binder cumulants and using the histogram analysis of the data that the introduction of nonmagnetic impurities to a spin system described by the two-dimensional Potts model with $q$ = 5 leads to a change of the first-order phase transition to a second-order phase transition.