The activity and function of many macromolecules in cellular environments are coupled with the binding of divalent ions such as Calcium or Magnesium. In principle, computer simulations can be used to understand molecular level aspects of how those macromolecules interact with ions. However, most of the force fields available today often fail to accurately reproduce the properties of divalent ions in aqueous environments. Here we develop a classical non polarizable force field for aqueous alkaline earth metal halides (MX2) where M = Mg2+, Ca2+, Sr2+, Ba2+ and X = Cl-, Br-, I- for bimolecular simulations which is compatible with the SPC/E water model. This new force field parameters are developed to reproduce the experimental Kirkwood-Buff integrals. Since this new force field can reproduce the experimental Kirkwood-Buff integrals for most concentrations of the respective salts, they are capable of reproduce the experimental activity derivatives, partial molar volumes, and excess coordination numbers. Use of these new models in MD simulations also leads to reasonable diffusion constants and dielectric decrements.

Kirkwood-Buff derived force field for aqueous alkali earth metal halides

251st National Meeting (2016)

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