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Application of Static Charge Transfer within an Ionic‐Liquid Force Field and Its Effect on Structure and Dynamics
Author(s) -
Youngs Tristan G. A.,
Hardacre Christopher
Publication year - 2008
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200800200
Subject(s) - ionic liquid , chemical physics , chemistry , partial charge , molecular dynamics , ion , ionic bonding , force field (fiction) , intermolecular force , diffusion , ab initio , charge (physics) , scaling , ionic potential , ab initio quantum chemistry methods , computational chemistry , thermodynamics , molecule , physics , quantum mechanics , organic chemistry , geometry , mathematics , catalysis
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 an alternative to computationally expensive polarisable force fields.