Ziff, Gulari and Barshad were the first to demonstrate kinetic phase transitions in a conceptual model for CO oxidation on the surface of a heterogeneous catalyst [R. M. Ziff, E. Gulari, Y. Barshad (1986) Phys. Rev. Lett. 56: 2553]. Using a mechanism that includes the non-dissociative adsorption of CO, the dissociative adsorption of O2, and the fast CO oxidation reaction Ziff et al., found a second order phase transition from an O-poisoned regime to a reactive regime, and a first order transition from the reactive to the CO-poisoned regime. Such a model can be easily set up in Zacros: this tutorial explains how to create the necessary input files.

The conceptual CO oxidation model by Ziff, Gulari and Barshad (ZGB) served as the first demonstration of kinetic phase transitions in heterogeneous catalytic systems.1 The model includes 3 irreversible events: non-dissociative adsorption of CO, dissociative adsorption of O2, and fast reaction between an O adatom and a CO adsorbate. Such a model can be easily set up in Zacros. In this tutorial we will discuss how to create the input files for such a simulation. By changing the molar fractions of the CO and O2 species, one can reproduce the phase diagram of the original paper by Ziff et al.1

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