(222au) Development and Evaluation of the Simple Models of Aqueous Electrolytes

Vlcek, L., Oak Ridge National Laboratory
Chialvo, A. A., Oak Ridge National Laboratory

Simple non-polarizable models of aqueous electrolytes underlie the majority of current geochemical and biochemical molecular simulations. To evaluate the reliability and predictive qualities of such studies, it is necessary to understand the limitations of the molecular force fields. Here we present the results of our effort to identify and overcome some of the main limiting factors of the existing simple models.

First, we analyze relationships between experimental structural, dynamic, and thermodynamic properties and individual force field parameters. Our main focus is on the proper choice of reference experimental data for absolute single ion thermodynamics and utilizing known correlations between solvation entropies and tracer diffusivities. Subsequently, we use this information to construct empirical simple (Lennard-Jones potential and point charges) models of common mono- and divalent ions. These include alkali metal and alkaline earth cations paired with halide and oxo-anions. Finally, the limits of the resulting force field  are evaluated and compared to other models.

Acknowledgements. This work was supported by the Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences, U.S. Department of Energy.