Critical behavior in an atomistic model for a bistable surface reaction: CO oxidation with rapid CO diffusion.
We analyze critical behavior associated with the loss of bistability for an atomistic model for CO oxidation on surfaces in the limit of infinite diffusion of CO. The model includes infinite nearest-neighbor repulsions between adsorbed immobile O. We use a "hybrid" treatment incorporating a lattice-gas description of the O adlayer, but tracking just the number of adsorbed CO (which are randomly distributed on non-O sites). The critical exponents obtained from a finite-size-scaling analysis on LxL site surfaces with periodic boundary conditions show that the "hybrid" reaction model belongs to the mean-field universality class, despite strong spatial correlations in the O adlayer. We also quantify finite-size effects in the global bifurcation diagram, revealing a significant shift of the bistable region with decreasing system size. Our study elucidates fluctuation effects observed in experiments of CO oxidation on the nanoscale facets of metal-field emitter tips.
Pavlenko
N
N
Institut für Physikalische Chemie und Elektrochemie, Universität Hannover, Callinstrasse 3-3a, D-30167 Hannover, Germany.
Imbihl
R
R
Evans
J W
JW
Liu
Da-Jiang
DJ