Chemical Potentials, Activity Coefficients, and Solubility in Aqueous NaCl Solutions: Prediction by Polarizable Force Fields.

0472724 - ÚCHP 2020 RIV US eng J - Journal Article
Moučka, F. - Nezbeda, Ivo - Smith, W.R.
Chemical Potentials, Activity Coefficients, and Solubility in Aqueous NaCl Solutions: Prediction by Polarizable Force Fields.
Journal of Chemical Theory and Computation. Roč. 11, č. 4 (2015), s. 1756-1764. ISSN 1549-9618. E-ISSN 1549-9626
Grant - others:NSERC(CA) OGP1041
Institutional support: RVO:67985858
Keywords : monte-carlo simulations * molecular-dynamic simulations * free-energy
OECD category: Physical chemistry
Impact factor: 5.301, year: 2015
Method of publishing: Limited access
https://pubs.acs.org/doi/pdf/10.1021/acs.jctc.5b00018

We describe a computationally efficient molecular simulation methodology for calculating the concentration dependence of the chemical potentials of both solute and solvent in aqueous electrolyte solutions, based on simulations of the salt chemical potential alone. We use our approach to study the predictions for aqueous NaCl solutions at ambient conditions of these properties by the recently developed polarizable force fields (FFs) and by the nonpolarizable JC FF of Joung and Cheatham tailored to SPC/E water. We also consider their predictions of the concentration dependence of the electrolyte activity coefficient, the crystalline solid chemical potential, the electrolyte solubility, and the solution specific volume. We first highlight the disagreement in the literature concerning calculations of solubility by means of molecular simulation in the case of the JC FF and provide strong evidence of the correctness of our methodology based on recent independently obtained results for this important test case. We then compare the predictions of the three FFs with each other and with experiment and draw conclusions concerning their relative merits, with particular emphasis on the salt chemical potential and activity coefficient vs concentration curves and their derivatives. The latter curves have only previously been available from KirkwoodBuff integrals, which require approximate numerical integrations over system pair correlation functions at each concentration. Unlike the case of the other FFs, the AH/BK3 curves are nearly parallel to the corresponding experimental curves at moderate and higher concentrations. This leads to an excellent prediction of the water chemical potential via the GibbsDuhem equation and enables the activity coefficient curve to be brought into excellent agreement with experiment by incorporating an appropriate value of the standard state chemical potential in the Henry Law convention.
Permanent Link: http://hdl.handle.net/11104/0269952