3-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 un reactive phases where the surface is saturated with one monomer specie s. The transitions from the reactive phase are all continuous, while t he transitions between poisoned phases are first order. Of particular interest are the bicritical points where the reactive phase simultaneo usly meets two poisoned phases. A mean-field cluster analysis fails to predict all of the qualitative features of the phase diagram unless c orrelations up to triplets of adjacent sites are included. Scaling pro perties of the continuous transitions and the bicritical points are st udied using dynamic Monte Carlo simulations. The transition from the r eactive to a saturated phase shows directed percolation critical behav ior, while the universal behavior at the bicritical point is in the ev en branching annihilating random walk class. The crossover from bicrit ical to critical behavior is also studied.