Application of static charge transfer within an ionic-liquid force field and its effect on structure and dynamics

Tristan Youngs, Christopher Hardacre

Research output: Contribution to journalArticlepeer-review

124 Citations (Scopus)

Abstract

The effects of linear scaling of the atomic charges of a reference potential on the structure, dynamics, and energetics of the ionic liquid 1,3-dimethylimidazolium chloride are investigated. Diffusion coefficients that span over four orders of magnitude are observed between the original model and a scaled model in which the ionic charges are +/- 0.5 e. While the three-dimensional structure of the liquid is less affected, the partial radial distribution functions change markedly-with the positive result that for ionic charges of +/- 0.7 e, an excellent agreement is observed with ab initio molecular dynamics data. Cohesive energy densities calculated from these partial-charge models are also in better agreement with those calculated from the ab initio data. We postulate that ionic-liquid models in which the ionic charges are assumed to be +/- 1 e overestimate the intermolecular attractions between ions, which results in overstructuring, slow dynamics, and increased cohesive energy densities. The use of scaled-charge sets may be of benefit in the simulation of these systems-especially when looking at properties beyond liquid structure-thus providing on alternative to computationally expensive polarisable force fields.
Original languageEnglish
Pages (from-to)1548-1558
Number of pages11
JournalChemPhysChem
Volume9
Issue number11
DOIs
Publication statusPublished - 04 Aug 2008

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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