Ion clusters and ion-water potentials in MD-simulations

TL;DR

This paper investigates the cause of unrealistic cation-cation associations in molecular simulations of aqueous ionic solutions, revealing that overly deep cation-water potentials in pair-potential models are a key factor.

Contribution

The study identifies the impact of overly deep cation-water potentials on ion association artifacts and provides insights into improving molecular simulation accuracy.

Findings

Unrealistic cation-cation associations are linked to deep cation-water potentials.

Pair-potential approximation contributes to the problem.

Insights for better potential modeling in MD simulations.

Abstract

A well known, if little documented, problem in many molecular simulations of aqueous ionic solutions at finite concentrations is that unrealistic cation-cation associations are frequently found. One might suspect a defect in the ion-ion interaction potentials, about which not much is known. However, we show that this phenomenon can also be traced to the fact that, in the pair-potential approximation, the cation-water potentials are too deep compared with the other ones and we investigate this phenomenon in some detail. We then attempt to draw some general conclusions.