Determination of the basic timescale in kinetic Monte Carlo simulations by comparison with cyclic-voltammetry experiments

Abstract

While kinetic Monte Carlo simulations can provide long-time simulations of the dynamics of physical and chemical systems, it is not yet possible in general to identify the inverse Monte Carlo attempt frequency with a physical timescale in any but the simplest systems. Here we demonstrate such an identification by comparing simulations with experimental data. Using a dynamic lattice-gas model for the electrosorption of Br on Ag(1 0 0), we measure the scan-rate dependence of the separation between positive-and negative-going peaks in cyclic voltammetry and compare simulated and experimental peak separations. By adjusting the Monte Carlo attempt frequency, good agreement between simulated and experimental peak separations is achieved. It is also found that the uniqueness of the determination depends on the relative values of the adsorption/desorption and diffusion free-energy barriers.

Microstructure and velocity of field-driven solid-on-solid interfaces moving under stochastic dynamics with local energy barriers

“…Even in cases where soft dynamics are the more appropriate choice, as for solidification or adsorption problems where the driving force is a chemical-potential difference, [12,13,27,28,29] the results can depend significantly on which soft dynamics are chosen. The spin classes in the anisotropic square-lattice SOS model.…”

Cl electrosorption on Ag(1 0 0): Lateral interactions and electrosorption valency from comparison of Monte Carlo simulations with chronocoulometry experiments

“…A meanfield approach is not sufficient, even for the description of one of the simplest halide-electrosorption systems Br/Ag(100). However, a simple lattice-gas model with constant parameters is sufficient to describe its equilibrium [2,3], and dynamic [4] properties. While the electrosorption of Br on single-crystal Ag(100) from aqueous solution has been extensively studied as an example of adlayer formation in an electrochemical system [2,5,6,7,8], less attention has been given to the electrosorption of Cl [3,9,10] on Ag(100).…”

New cyclic voltammetry method for examining phase transitions: Simulated results

“…For a discussion of the relation between this simulated time unit and real, physical time, see Ref. [7]. In each MCS of the simulation, an adsorption site is chosen at random and a move (adsorption, desorption, or diffusion) is attempted.…”

“…A weighted list of the probabilities for accepting each of these moves during one MCS is constructed using Eq. (5) below, and used to calculate the probabilities R(FjI) of the individual moves between the initial state I and final state F. The probability for the system to remain in the initial configuration at the end of the time step is consequently R(I jI) = 1 À R F6 ¼I R(F jI) [7,8].…”

“…Second, we study a lattice-gas model with repulsive lateral interactions and nearest-neighbor exclusion (similar to the model of halide adsorption on Ag(1 0 0), described in Refs. [7][8][9][10]), being similarly driven through its continuous phase transition. Some preliminary results of this work have been submitted for publication elsewhere [11].…”