Does an electronic continuum correction improve effective short-range ion-ion interactions in aqueous solution?

Abstract

Non-polarizable force fields for hydrated ions not always accurately describe short-range ion-ion interactions, frequently leading to artificial ion clustering in bulk aqueous solutions. This can be avoided by adjusting the nonbonded anion-cation or cation-water Lennard-Jones parameters. This approach has been successfully applied to different systems, but the parameterization is demanding owing to the necessity of separate investigations of each ion pair. Alternatively, polarization effects may effectively be accounted for using the electronic continuum correction (ECC) of Leontyev et al. [J. Chem. Phys. 119, 8024 (2003)], which involves scaling the ionic charges with the inverse square-root of the water high-frequency dielectric permittivity. ECC has proven to perform well for monovalent salts as well as for divalent salts in water. Its performance, however, for multivalent salts with higher valency remains unexplored. The present work illustrates the applicability of the ECC model to trivalent KPO and divalent KHPO in water. We demonstrate that the ECC models, without additional tuning of force field parameters, provide an accurate description of water-mediated interactions between salt ions. This results in predictions of the osmotic coefficients of aqueous KPO and KHPO solutions in good agreement with experimental data. Analysis of ion pairing thermodynamics in terms of contact ion pair (CIP), solvent-separated ion pair, and double solvent-separated ion pair contributions shows that potassium-phosphate CIP formation is stronger with trivalent than with divalent phosphate ions.

Influence of effective polarization on ion and water interactions within a biomimetic nanopore

“…proteins, lipids etc.) which are already routinely parameterized with partial charges to account implicitly for electronic polarization (5,32).…”

“…Neglecting polarizability therefore has consequences for accurately modelling the properties of polarizable anions where many key effects of these ions arise from their electronic responses. For example, the use of NP force fields can lead to inaccuracies in describing short-range ion-water and ion-ion interactions as well as overestimating ion clustering (32,33). Leontyev & Struchebrukhov (34), and expanded upon by Jungwirth et al (26,(35)(36)(37), that the lack of polarization in NP force fields can be compensated for by implicitly accounting for electronic polarization effects through an electronic continuum correction (ECC).…”

On the transferability of ion parameters to the TIP4P/2005 water model using molecular dynamics simulations

“…This choice of partial charges, known as Electronic Charge Correction (ECC), was argued to be necessary in a nonpolarizable model to account for the electronic contribution to the dielectric constant. 45,46 ECC has received increased attention in recent years 24,29,[47][48][49] but remains unusual for most ion force fields.…”

Interfacial and bulk properties of concentrated solutions of ammonium nitrate

“…32,43,44 The importance of the ECC model manifests itself for both monovalent and multivalent ions, as they are capable of polarising their surrounding water molecules. 30,[45][46][47][48][49] Mason et al 46 and Pegado et al 50 showed that, predictions of the properties of aqueous salt solutions in the bulk improved significantly using the electronic continuum correction model compared with non-polarisable simulations. However, the applicability of the ECC model has not been fully examined for liquid-liquid and liquid-vapour interfaces.…”