A Kirkwood-Buff Derived Force Field for Aqueous Alkali Halides

Abstract

A classical nonpolarizable force field is presented for the simulation of aqueous alkali halide solutions (MX), where M = Li+, Na+, K+, Rb+, Cs+ and X = F−, Cl−, Br−, I−, and their interactions with biomolecules. The models are specifically designed to reproduce the experimental Kirkwood-Buff integrals, and thereby the solution salt activities, as a function of salt concentration. Additionally, we demonstrate that these models reasonably reproduce other experimental properties including ion diffusion constants, dielectric decrements, and the excess heats of mixing. The parameters are developed by considering the properties of aqueous NaX and MCl solutions using a previously established model for NaCl. Transferability of the parameters to other salts is then established by the successful simulation of additional aqueous salt solutions, KI and CsBr, not originally included in the parameterization procedure.

Kirkwood-Buff analysis of aqueous N-methylacetamide and acetamide solutions modeled by the CHARMM additive and Drude polarizable force fields

“…81,91,94,[96][97][98][99][100][101] The results showed that without introducing polarization good agreement with experimental KB data can be obtained. The present study demonstrated that the polarizable Drude force field, which was not developed by targeting experimental KB data, can also achieve almost the same degree of accuracy compared to KBFF, except for activity derivative and excess Gibbs free energy, which will be the focus in our future force field optimization efforts.…”

The properties of residual water molecules in ionic liquids: a comparison between direct and inverse Kirkwood–Buff approaches

“…20,21. Hence, assuming that IL cations and anions contribute equivalently, one can define the ion-ion KB integral G 22 in presence of cations (+) and anions (−) according to [88][89][90] …”

Osmotic pressure of aqueous electrolyte solutions via molecular simulations of chemical potentials: Application to NaCl

“…A Lennard-Jones (LJ) potential with parameters ε and models the nonpolar interaction between oxygen sites. The complete pair potential between two water molecules is expressed as [30] u ij = u LJ,ij + u PC,ij (16) where…”

“…The parameters of aqueous electrolyte FFs have typically been determined by fitting simulation results to approximate high-level ab initio computational data or to various types of experimental data, including the infinite dilution properties of hydration free energy, enthalpy and entropy for single ions [22,10,19], chemical potential derivatives related to experimental values of the solution compressibility and density at a single concentration in conjunction with Kirkwood-Buff integrals [63,58,16], low-concentration densities [11], and solid salt properties such as lattice constants [22,63]. FFs determined by these means have frequently been unable to satisfactorily predict more complex and composition-dependent thermodynamic properties, and thus the composition dependence of solution chemical potentials [44], and the osmotic pressure, [35,24,34,56], ˘, have recently been used as alternative approaches to fit FF parameters.…”