We investigated the dynamic properties of alkali halide solutions (NaCl, NaF, NaBr, NaI, LiCl, and KCl) using molecular dynamics simulations and several nonpolarizable, polarizable, and scaled-charge models to probe hydration structure behavior. Shear viscosity was obtained as a function of concentration with very low statistical uncertainties to allow for high precision calculations of the Jones-Dole viscosity B-coefficient. These are the first predictions of the B-coefficient from molecular simulations for fully atomistic systems of electrolyte solutions. We calculated diffusion coefficients with rigorous finite-size corrections to access ion mobilities that provide insights towards single ion hydration behavior. We find that all models studied, even polarizable and scaled-charge models, quantitatively over-predicted water structuring ability but qualitatively followed the experimental Hofmeister series. In fact, all ions were represented as kosmotropes based on B-coefficient and diffusion predictions, even for ions experimentally found as chaotropes. These observations indicate that the water-ion interactions in these models are not well represented and additional interactions such as charge transfer must be incorporated in future model development in order to better represent electrolyte solution properties.

Dynamic properties of aqueous electrolyte solutions from nonpolarizable, polarizable, and scaled-charge models

2019 Fall National Meeting

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