Molecular Force Field Development for Aqueous Electrolytes: 2. Polarizable Models Incorporating Crystalline Chemical Potential and Their Accurate Simulations of Halite, Hydrohalite, Aqueous Solutions of NaCl, and Solubility

Abstract

The current state-of-the-art force fields (FFs) for Na + a Cl − ions are not capable of simultaneously predicting the thermodynamic properties of the aqueous solution and the crystalline phase. This is primarily due to an oversimplification of the interaction models used but partially also due to the insufficient parametrization of the FFs. We have devised a straightforward and simple parametrization procedure for determining the ion-ion interaction parameters in complex molecular models of NaCl electrolytes which involves fitting the density, lattice energy and chemical potential of crystalline NaCl at ambient conditions. Starting from the AH/BK3 and MAH/BK3 FFs, the parametrization approach is employed to develop a complex and accurate polarizable molecular model for the NaCl electrolyte by parametrizing the ion-ion interactions. The performance of the refined polarizable NaCl FF is assessed by evaluating the different thermodynamic and mechanical properties of the crystal, density of crystalline and molten NaCl along with the melting temperature, properties of aqueous solutions, and the structure and stability of hydrohalite. The simulation results confirm the superiority of the refined FF in comparison with the existing state-of-the-art FFs to accurately predict a wide range of system properties in different NaCl phases, including NaCl aqueous solubility. The refined FF may find applications in the accurate simulations of NaCl electrolytes including inhomogeneous environment, phase equilibria and interfaces, and metastable states. Finally, the parametrization strategy is robust and general, and can be used to devise molecular models for other electrolytes.

Single-Particle Dynamics at the Intrinsic Surface of Aqueous Alkali Halide Solutions

“…Further, this effect is considerably stronger for the nonpolarizable JC than for the polarizable AH/BK3 force field. Similar improvement of the results caused by using a polarizable model was also reported in a recent paper by Dočkal et al for NaCl solutions . It should be emphasized, however, that, although both models can very well reproduce the experimental trend in the bulk phase of the 1.3 M solution, the D / D 0 ratio shows a rather strong dependence on the salt concentration also (its value scattering between about 0.6 and 1.2 up to the concentration of 6 M), and our present results do not imply anything about this concentration dependence.…”

Predicting the properties of salt water using neural network potentials and continuum solvent theory

“…These parameters are invariably fitted to reproduce experimental measurements. [5][6][7] The most prominent example of this are the Pitzer equations. [8] This is a crude solution as there are large gaps and uncertainties in existing experimental databases.…”

Elucidation of Molecular‐level Mechanisms of Oxygen Atom Reactions with Chlorine Ion in NaCl Solutions using Molecular Dynamics Simulations Combined with Density Functional Theory

“…The average and standard deviation of the reaction time are 135.89 fs and 47.58 fs, respectively. Compared to the reaction times of the O( 1 D)‐NaCl‐63H 2 O and O( 1 D)‐4NaCl‐63H 2 O systems, the concentration decreased the diffusion coefficients of H 2 O, Na + , and Cl − , [5,6] but the reaction rates of O and Cl − increased about 7 times.…”

“…investigated atomic‐level mechanisms of ionic dissociation of NaCl in a small cluster NaCl(H 2 O) 6 [3] . Although the diffusion coefficients of sodium and chloride ions in aqueous solutions cannot be precisely and quantitatively predicted, qualitative results indicate that the diffusion coefficients of H 2 O, Na + , and Cl − ions decreased as the concentration of NaCl increased [4,5] . However, the molecular‐level mechanisms of reactions involving ions and electrons in an aqueous solution are not always clear [6] …”

“…[3] Although the diffusion coefficients of sodium and chloride ions in aqueous solutions cannot be precisely and quantitatively predicted, qualitative results indicate that the diffusion coefficients of H 2 O, Na + , and Cl À ions decreased as the concentration of NaCl increased. [4,5] However, the molecular-level mechanisms of reactions involving ions and electrons in an aqueous solution are not always clear. [6] Previously, experimental works have used non-thermal atmospheric-pressure plasma (NTAP) in contact with aqueous solutions to study the macroreaction mechanisms of plasmainduced radicals and aqueous electrolyte solutions.…”