MONTE-CARLO SIMULATIONS OF OSCILLATIONS

Results of Monte Carlo simulations of CO oxidation with site blocking, and of the Lotka model (A(gas) --> A(ads), B(ads) --> B(gas), A(ads) + B(ads) --> 2B(ads)) are presented. The introduction of a site blocki ng adsorbate can lead to oscillations in do oxidation. The system is b istable for certain coverages of the site blocking adsorbate; adsorpti on and desorption of that adsorbate drive the system from one stable s tate to the other and back The oscillations in the Lotka model are due to avalanches of A's that are converted into B's by the autocatalytic step. Normal rate equations are unable to describe these systems corr ectly.