Monomer-dimer reaction model with nearest-neighbor interactions at finite temperatures

We studied a monomer-dimer catalytic surface reaction model of the type 1 / 2A(2)+BA-->A2B, where interactions between nearest-neighbor species and the temperature of the catalyst are considered. Through Monte Carlo simulations we determined the phase diagram of the model in the plane temperature versus partial pressure of the BA molecules in its gaseous phase. We found that the transition between the A-poisoned state and the active one is always continuous and the associated critical exponents are in the same universality class of the directed percolation (DP). On the other hand, the transition from the active state to the BA-poisoned one changes from continuous to first order for a given temperature value. The critical exponents of the continuous branch belong also to the DP universality class. For a small range of values of the partial pressure of BA and very low temperatures, we observe the formation of an inactive sublattice structure inside the active phase.