Simulating Electrode-Solution Interfaces Using 3D Cellular Automation

Abstract

A three-dimensional cellular automation model is applied to study the spatial distribution of water molecules contacting a structureless planar electrode. Water molecules occupying each cell are modeled as electric dipoles comprising separated positive and negative charges. Electrostatic interactions between cells are computed to determine local torques on water dipoles. Meanwhile, the dipole rotational response is modeled as a thermally activated event. Interfacial phenomena, such as the parallel alignment of water molecules to a neutral planar electrode emerge spontaneously from the simulation. When solvated ions are available in the water, attraction and repulsion due to charges cause a non-uniform distribution of anions and cations. The simulation results presented here, including the computed distribution profiles for anions and cations influenced by the electrode charge density, the resulting electric fields, and the variation of the dielectric constant of water, are consistent with theoretical calculations and existing simulations based on molecular dynamics.