DAMAGE SPREADING IN THE ZIFF-GULARI-BARSHAD MODEL

The spreading of initial damage globally distributed on the system is studied in a dimer-monomer irreversible reaction process (i.e., the ZGB model [Ziff, Gulari, and Barshad, Phys. Rev. Lett. 56, 2553 (1986)]) in two dimensions. It is found that the damage heals within the poisoned states but spreads within the reactive regime. Both the frozen-chaotic and reactive-poisoned irreversible transitions occur at the same critical points and are of the same order. However, the order parameter critical exponents at the second-order transition are different, suggesting that damage spreading introduces a new dynamic critical behavior. A variant of the ZGB model (e.g., the ZGBER model), which is obtained by the addition of an Eley-Rideal reaction step, is also studied. In two dimensions, damage heals within the poisoned state. However, in contrast to the ZGB model, within the reactive regime, a frozen-chaotic transition is found to occur at a different critical point than the poisoning-reactive transition. At the frozen-chaotic critical point the damage heals according to a power-law behavior, D (t) is-proportional-to t(-delta), with delta congruent-to 0.65. The order parameter critical exponent is also determined and the fact that damage spreading introduces a new kind of dynamic critical behavior is established. Damage healing is observed in one dimension for the ZGBER model.