Monte Carlo study of CO oxidation on an anisotropic surface

B. Yu, Louisiana State University
D. A. Browne, Louisiana State University
P. Kleban, University of Maine


It is well established that anisotropy does not affect the critical behavior of a system in thermodynamic equilibrium that undergoes a second-order phase transition. We study here an anisotropic kinetic model for heterogeneous catalysis that mimics the oxidation of CO on the (110) surface of a transition metal like Pd. We have mapped out the phase diagram of possible steady states for various anisotropic reaction and absorption processes as a function of the O2/CO adsorption rate and the CO diffusion rate. The phase diagram depends upon the amount of anisotropy and exhibits both a first-order and a second-order phase transition for a reactive to an unreactive steady state. We have examined the critical behavior at the second-order phase transition with finite-size scaling and have found that this model belongs to the directed percolation universality class irrespective of the anisotropy. © 1991 The American Physical Society.