Molecular Models of Electrolyte Aqueous Solutions: Simulation Study on Limits of Their Applicability

Eleven of the most common non polarizable SPC/E-based aqueous NaCl solution force fields and two polarizable force fields based on SWM4-DP and BK3 models of water have systematically been examined with respect to the accuracy of their prediction of the solution density and chemical potential over the entire concentration range at ambient pressure and temperature. The density was obtained by Monte Carlo simulations at constant pressure, temperature, and number of molecules. Dependence of the electrolyte chemical potential on concentration was obtained using a recently developed Osmotic Ensemble Monte Carlo method [1] simulating the system at constant pressure, temperature, number of solvent molecules, and electrolyte chemical potential. Polarizable models were simulated using multiparticle move Monte Carlo method [2].

It is found that the results of the force fields considered are scattered over a wide range of values, and none is capable of producing quantitatively accurate results over the entire concentration range for the properties considered [3]. The polarizable models reproduce the slope of the electrolyte chemical potential vs. concentration at high concentrations better than the SPC/E-based models.

References

[1] F. Moučka, M. Lísal, J. Škvor, J. Jirsák, I. Nezbeda, W. R. Smith J. Phys. Chem B 115, 7849(2011).

[2] F. Moučka, I. Nezbeda, W. R. Smith Mol. Simul. 39, 1125(2013).

[3] F. Moučka, I. Nezbeda, W. R. Smith J. Chem. Phys. 138, 154102(2013).