Study of a monomer-monomer reaction system with short-range repulsive interactions

M. A. SANSERVINO ; A. C. LÓPEZ; E. V. ALBANO; R. A. MONETTI

EUROPEAN PHYSICAL JOURNAL B - CONDENSED MATTER

SPRINGER

Lugar: Berlin; Año: 2004 vol. 40 p. 305 - 312

1434-6028

Abstract. The critical behavior of an interacting two species catalytic surface reaction model is studiedby means of Monte Carlo simulations and a mean-field approach. The model has two parameters, namelythe relative adsorption rate of species pA and a short-range repulsive interaction r between the same typeof adsorbed species. The system exhibits an stationary reactive phase and two symmetrically equivalentabsorbing phases. These latter phases are unique and correspond to surfaces saturated by a single type ofreacting species. For r > 0 ∧ r = 1, the system exhibits a second-order phase transition that belongs tothe directed percolation (DP) universality class. However, in the absence of repulsive interaction (r = 0),a bicritical point is found at pA = 1/2 whose critical behavior is compatible with dynamical mean-fieldexponents. Our findings indicate that the bicritical point belongs to the Voter Model universality class,whose upper critical dimension is dc = 2. In addition, we propose a method to study the crossover fromMF to DP behavior based on the estimation of the crossover time Tc. We find that Tc diverges accordingto a power-law Tc ∝ r−μ as r → 0 where μ  1.17 ± 0.03 is the crossover exponent. For strong repulsion,a new transient effect appears associated with the onset of almost inactive ?chessboad? patterns.