title: Response of a catalytic reaction to periodic variation of the CO pressure: increased CO2 production and dynamic phase transition.
abstract: We present a kinetic Monte Carlo study of the dynamical response of a Ziff-Gulari-Barshad model for CO oxidation with CO desorption to periodic variation of the CO pressure. We use a square-wave periodic pressure variation with parameters that can be tuned to enhance the catalytic activity. We produce evidence that, below a critical value of the desorption rate, the driven system undergoes a dynamic phase transition between a CO2 productive phase and a nonproductive one at a critical value of the period and waveform of the pressure oscillation. At the dynamic phase transition the period-averaged CO2 production rate is significantly increased and can be used as a dynamic order parameter. We perform a finite-size scaling analysis that indicates the existence of power-law singularities for the order parameter and its fluctuations, yielding estimated critical exponent ratios beta/nu approximately 0.12 and gamma/nu approximately 1.77. These exponent ratios, together with theoretical symmetry arguments and numerical data for the fourth-order cumulant associated with the transition, give reasonable support for the hypothesis that the observed nonequilibrium dynamic phase transition is in the same universality class as the two-dimensional equilibrium Ising model.
authors.affiliation: Physics Department, Universidad Simón Bolívar, Apartado 89000, Caracas 1080, Venezuela.
authors.forename: Erik
authors.initials: E
authors.lastname: Machado
authors.forename: Gloria M
authors.initials: GM
authors.lastname: Buendía
authors.forename: Per Arne
authors.initials: PA
authors.lastname: Rikvold
authors.forename: Robert M
authors.initials: RM
authors.lastname: Ziff