Importance of Nuclear Quantum Effects on the Hydration of Chloride Ion

TL;DR

This study uses path-integral ab initio molecular dynamics to show that nuclear quantum effects weaken hydrogen bonding in chloride ion hydration, aligning well with experimental neutron scattering data and highlighting their importance in saline solution structure.

Contribution

It demonstrates the significant impact of nuclear quantum effects on chloride ion hydration structure, a factor often neglected in classical simulations.

Findings

NQEs weaken hydrogen bonds around chloride ions.

NQEs reduce chloride's disruptive effect on water structure.

Simulation results agree with neutron scattering data.

Abstract

Path-integral ab initio molecular dynamics (PI-AIMD) calculations have been employed to probe the nature of chloride ion solvation in aqueous solution. Nuclear quantum effects (NQEs) are shown to weaken hydrogen bonding between the chloride anion and the solvation shell of water molecules. As a consequence, the disruptive effect of the anion on the solvent water structure is significantly reduced compared to what is found in the absence of NQEs. The chloride hydration structure obtained from PI-AIMD agrees well with information extracted from neutron scattering data. Inparticular, the observed satellite peak in the hydrogen-chloride-hydrogen triple angular distribution serves as a clear signature of NQEs. The present results suggest that NQEs are likely to play acrucial role in determining the structure of saline solutions.