je9b00688_si_001.pdf (302.67 kB)
Activity Coefficients and Solubility of CaCl2 from Molecular Simulations
journal contribution
posted on 2019-10-17, 15:50 authored by Jeffrey
M. Young, Christopher Tietz, Athanassios Z. PanagiotopoulosWe
obtain the activity coefficients and lower bounds to the solubility
of CaCl2 in aqueous solutions at temperatures between 298.15
and 473.15 K using molecular simulations with three previously developed
nonpolarizable force fields. We find that a scaled-charge force field
gives incorrect activity coefficients at low concentration and has
a different absolute chemical potential than experiments, but still
predicts an accurate solubility for the calcium chloride dihydrate.
The two full-charge models have chemical potentials and activity coefficients
closer to experiments, but there is considerable variation between
them, with the chemical potentials differing by over 100 kJ·mol−1. The slow dynamics of the full-charge models at high
concentrations are unrealistic and require advanced sampling methods
to obtain the activity coefficients. We find that development of polarizable
models is likely necessary to accurately represent both thermodynamic
and transport properties of divalent electrolyte solutions.