molecular dynamics, aqueous electrolyte, electrode surface charge densities


Molecular dynamics simulations have been carried out for aqueous electrolyte solutions between model electrode surfaces. The effect of solvent model flexibility on bult and double layer properties was observed for electrode surface charge densities of 0, 0.1 and 0.2 and ion concentrations of 0, 0.5 and 1 M. Two flexible models were used to isolate the effects of flexibility from the effects of a change in the condensed-phase dipole moment. Model flexibility increases the pure water self-diffusion coefficient while a larger liquid diple moment substantially decreases it. There is an increase in ion contact adsorption and counter ion affinity with the flexible models, suggesting that the ions are less tightly colvated. This conclusion is consistent with observed enhancements of solvated ion densities near uncharged electrodes for the flexible water case. Mobile ions in high concentration quicly damp out the electric field even at high electrode charge densities, but for dilute ion concentration the field may extend to the center of the cell or beyond. In these cases it is more appropriate to integrate Poisson's equation from the electrode surface outward instead of the common method of assuming zero field at the center of the simulation cell. Using this methodology, we determine the voltage drop across the half-cell for both the rigid and flexible models. The half-cell voltage drop shows some dependence on ion concentration, but solvent flexibility has little effect on that behavior.

Original Publication Citation

C. G. Guymon, M. L. Hunsaker, J. N. Harb, D. Henderson, and R. L. Rowley, "Effects of solvent model flexibility on aqueous electrolyte behavior between electrodes", J. Chem. Phys. 118, 1195-122 (23)

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Peer-Reviewed Article

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Ira A. Fulton College of Engineering and Technology


Chemical Engineering