Tricritical point of the three-dimensional Potts model ($q = 4$) with quenched nonmagnetic disorder

The effect of quenched nonmagnetic impurities on the phase transitions in the three-dimensional Potts model with the number of spin states $q = 4$ for the case of the simple cubic lattice is studied using the Monte Carlo method. The phase transitions in this model are studied for spin density $p$ ranging from $1.0$ to $0.70$. The position of the tricritical point at the phase diagram is determined.