Revisiting the first-order irreversible phase transition of the Ziff-Gulari-Barshad model

The first-order irreversible phase transition (IPT) characteristic of the Z iff-Gulari-Barshad (ZGB) model is studied by means of extensive numerical s imulations. Using the constant-coverage method it is found that hysteresis effects hinder the location of the coexistence point. However, the hysteres is loop is unstable against a negligible small external perturbation, allow ing the determination of the coexistence point quite accurately. Also, by m eans of epidemic studies, an existing controversy on the occurrence of scal e invariance in the dynamical behaviour of the system at coexistence is res olved. Our findings reconcile the behaviour of the first-order IPTs of the ZGB model with their reversible counterparts.