Concentration Dependence of the Dielectric Permittivity, Structure, and Dynamics of Aqueous NaCl Solutions: Comparison between the Drude Oscillator and Electronic Continuum Models

Abstract

We report molecular dynamics simulations of aqueous sodium chloride solutions at T = 298 K and p = 1 bar in order to investigate the salt concentration dependence of the dielectric permittivity, the structure, and the dynamical properties. Different models were applied up to 7 m salt concentration: the Drude oscillator model with a negative Drude particle (SWM4-NDP), the TIP4P/2005-Reif nonpolarizable model, and an electronic continuum polarizable model (MDEC). Both SWM4-NDP and MDEC polarizable models were able to quantitatively reproduce the concentration dependence of the dielectric permittivity of NaCl aqueous solutions. On the contrary, the nonpolarizable TIP4P/2005 water model failed to quantitatively predict this concentration dependence. In contrast with the SWM4-NDP model, the MDEC model was unable to capture the concentration dependence of the structure and the dynamics of NaCl solutions. The SWM4-NDP model proved to be the most efficient polarizable model to reproduce quantitatively the concentration dependence of the dielectric permittivity, the dynamics, and the structure of NaCl solutions.