Phase Diagrams of the YK Surface-Reaction Model on 2D lattices with Exchange Diffusion

TL;DR

This study explores how exchange diffusion influences the phase diagrams of the Yaldram and Khan catalytic surface model on 2D lattices, revealing phase transitions and the conditions for active states through extensive Monte Carlo simulations.

Contribution

It provides new insights into the effects of exchange diffusion on phase behavior in catalytic surface models on square and hexagonal lattices.

Findings

Exchange diffusion promotes active phases at lower NO dissociation rates.

Both lattices exhibit continuous and discontinuous phase transitions.

At r_{NO}=1, the continuous transition is suppressed, favoring reactive states.

Abstract

In this work, we investigate the phase diagrams of the Yaldram and Khan catalytic surface model on square and hexagonal lattices when exchange diffusion is allowed for carbon monoxide (CO) and nitrogen (N) atoms. To reach our goal, we carried out steady-state Monte Carlo (MC) simulations over $4\times 10^5$ points, for both lattices, in order to obtain a framework of the steady reactive state of the model for different values of the nitric oxide dissociation rate, $r_{NO}$. The results show the emergence of steady reactive state for certain values of $r_{NO}$ and of exchange diffusion rate $x$ when the simulations take place on square lattices. Our findings on the hexagonal lattice also show that the diffusion of these species favors the appearance of the active phase for values of $r_{NO}$ lower than that found for the standard model. In addition, we observed that the system possesses a continuous phase transition and a discontinuous one separating the active phase from absorbing states for both lattices, except for $r_{NO}=1$ in which the continuous phase transition is destroyed and a steady reactive state emerges from the beginning since very small values of $x$.