N ov 1 99 6 The three species monomer - monomer model : A mean - field analysis and Monte Carlo study

We study the phase diagram and critical behavior of a one dimensional three species monomer-monomer catalytic surface reaction model. Static Monte Carlo simulations are used to roughly map out the phase diagram consisting of a reactive steady state bordered by three equivalent unreactive phases where the surface is saturated with one monomer species. The transitions from the reactive phase are all continuous, while the transitions between poisoned phases are first-order. Of particular interest are the bicritical points where the reactive phase simultaneously meets two poisoned phases. A mean-field cluster analysis fails to predict all of the qualitative features of the phase diagram unless correlations up to triplets of adjacent sites are included. Scaling properties of the continuous transitions and the bicritical points are studied using dynamic Monte Carlo simulations. The transition from the reactive to a saturated phase shows directed percolation critical behavior, while the universal behavior at the bicritical point is in the even branching annihilating random walk class. The crossover from bicritical to critical behavior is also studied. 05.70.Ln, 82.20.Mj, 82.65.Jv, 64.50.Ht Typeset using REVTEX