Critical behavior in an atomistic model for a bistable surface reaction: CO oxidation with rapid CO diffusion

Area of Science:

• Surface science
• Chemical kinetics
• Statistical mechanics

Background:

• CO oxidation on metal surfaces exhibits complex reaction kinetics and phase transitions.
• Bistability and critical phenomena are key features observed in these surface reactions.
• Understanding these phenomena is crucial for catalysis and materials science.

Purpose of the Study:

• To analyze critical behavior associated with the loss of bistability in an atomistic model for CO oxidation.
• To investigate the universality class of a "hybrid" surface reaction model.
• To quantify finite-size effects on the bistable region.

Main Methods:

• Atomistic modeling of CO oxidation with infinite CO diffusion and infinite nearest-neighbor repulsions for O.
• Hybrid treatment combining lattice-gas description for O and tracking adsorbed CO numbers.
• Finite-size-scaling analysis on LxL surfaces with periodic boundary conditions.

Main Results:

• The "hybrid" reaction model was found to belong to the mean-field universality class.
• Strong spatial correlations in the O adlayer did not alter the universality class.
• Finite-size effects were quantified, showing a significant shift in the bistable region with decreasing system size.

Conclusions:

• The study elucidates fluctuation effects relevant to experimental observations of CO oxidation on nanoscale facets.
• The findings contribute to understanding critical phenomena in surface reactions.
• The hybrid model provides insights into the interplay of adlayer structure and reaction dynamics.