The influence of lateral interactions on the critical behavior of a dimer-monomer surface reaction model

The ZGB model [Ziff et al., Phys. Rev. Lett. 56, 2553 (1986)] for a monomer–dimer surface reaction process of the type A+(1/2)B2→AB, exhibits two irreversible phase transitions (IPT) from a stationary regime with AB production for p1A≤pA≤p2A, to poisoned states with B (A)-species for pA≤p1A (pA≥p2A), respectively, where pA is the mole fraction of A-species in the gas phase and piA (i=1, 2) are critical points. A generalization of the ZGB model in order to account for both attractive and repulsive interactions between the reactants is presented and discussed. It is found that in most cases the first order IPT at p2A becomes of second order and the critical points are shifted. For some particular choices of the interactions energies it is found that the second order IPT at p1A becomes of first order. Also, a first order IPT from the reactive state to a effectively poisoned regime where A-species are adsorbed forming a c(2×2) metastable structure is obtained.