The stochastic simulation algorithm (SSA) provides a general framework for the simulation of the time evolution of a given system containing reacting chemical species. Being a different approach to the chemical master equation, the SSA takes into account the intrinsic probabilistic nature of chemical dynamics. For microscopic and diluted systems, where fluctuations take a major role in their time evolution, the deterministic reaction rate equations (RRE) fails to give correct predictions. Therefore, in order to be able to match, and eventually predict, the experimental response of such systems, the SSA approach is far superior than the RRE, if not strictly necessary, providing more informations than just a fit to the experimental measurement. However, the SSA provides no straightforward way to simulate electrochemical systems, which are surface reactions driven by an electric, usually external, driving force; and the coupled electric response. By considering the connection between the SSA and the RRE, with its formulation of electrochemical kinetics, an attempt is made to perform the simulation of an electrochemical system within the framework of the SSA. A generalized electrochemical reaction propensity function is proposed, along with equations to provide the corresponding electric response of the system, namely the electrode potential and the electric current for galvano and potentiostatic experiments, respectively. The proposed equations reproduce the expected behaviour of simple systems correctly, as shown in the Figure for the galvanostatic response of the prototypical reaction S1 ↔ S2 + e-. It is expected that the full array of methods relative to the SSA to be directly applicable to electrochemical systems.

Stochastic simulation algorithm applied to electrochemical systems

251st National Meeting (2016)

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