Kinetic Monte Carlo Simulations: Step fluctuations on silver electrodes

KAY POETTING; PAOLA QUAINO; HARALD IBACH; WOLFGANG SCHMICKLER

Sevilla

Congreso; The 59th Annual Meeting of the International Society of Electrochemistry-ISE; 2008

The International Society of Electrochemistry - ISE

It is well known that point defects on metal surfaces are associated with a local dipolemoment, which can be explained in terms of the Smoluchowski effect, a redistribution of the electronic charge. At an ideally polarizable solid/liquid interface, these local electric dipoles interact with the double-layer field (Edl). Since the dipole moment depend on the local environment, its magnitude at transition states is different than at equilibrium positions. Hence, this dipole-field interaction produces a change of the diffusion rates, affecting the step and island dynamics of the system. In this work, we present a combination of DFT calculations and kinetic Monte Carlo simulations (KMC) to study the step fluctuations through the evaluation of the stiffness coefficient as a function of the temperature (350K-650K), and we mainly focus on the effect of an electric field on the kinetics of the fluctuations and its influence on the step stiffness. For this purpose, all the diffusion barriers were calculated within the embedded atom method, the surface dipole moments were obtained using density functional theory, and the evaluation of the stiffness coefficients was based on the one-dimensional capillary wave theory. Our results indicate a strong effect o f the f ie ld on energetic parameters l ike the step line stiffness and the kink energy, corresponding to stronger fluctuations in the system at higher electrode potentials.