Revisiting OPLS Force Field Parameters for Ionic Liquid
Simulations
Brian Doherty
Xiang Zhong
Symon Gathiaka
Bin Li
Orlando Acevedo
10.1021/acs.jctc.7b00520.s002
https://acs.figshare.com/articles/dataset/Revisiting_OPLS_Force_Field_Parameters_for_Ionic_Liquid_Simulations/5616727
Our
OPLS-2009IL force field parameters (<i>J. Chem. Theory
Comput.</i> <b>2009</b>, <i>5</i>, 1038–1050)
were originally developed and tested on 68 unique ionic liquids featuring
the 1-alkyl-3-methylimidazolium [RMIM], <i>N</i>-alkylpyridinium
[RPyr], and choline cations. Experimental validation was limited to
densities and a few, largely conflicting, heat of vaporization (Δ<i>H</i><sub>vap</sub>) values reported in the literature at the
time. Owing to the use of Monte Carlo as our sampling technique, it
was also not possible to investigate the reproduction of dynamics.
The [RMIM] OPLS-2009IL parameters have been revisited in this work
and adapted for use in molecular dynamics (MD) simulations. In addition,
new OPLS-AA parameters have been developed for multiple anions, i.e.,
AlCl<sub>4</sub><sup>–</sup>, BF<sub>4</sub><sup>–</sup>, Br<sup>–</sup>, Cl<sup>–</sup>, NO<sub>3</sub><sup>–</sup>, PF<sub>6</sub><sup>–</sup>, acetate, benzoate
bis(pentafluoroethylsulfonyl)amide, bis(trifluoroethylsulfonyl)amide,
dicyanamide, formate, methylsulfate, perchlorate, propanoate, thiocyanate,
tricyanomethanide, and trifluoromethanesulfonate. The computed solvent
densities, heats of vaporization, viscosities, diffusion coefficients,
heat capacities, surface tensions, and other relevant solvent data
compared favorably with experiment. A charge scaling of ±0.8
e was also investigated as a means to mimic polarization and charge
transfer effects. The 0.8-scaling led to significant improvements
for Δ<i>H</i><sub>vap</sub>, surface tension, and
self-diffusivity; however, a concern when scaling charges is the potential
degradation of local intermolecular interactions at short ranges.
Radial distribution functions (RDFs) were used to examine cation–anion
interactions when employing 0.8*OPLS-2009IL and the scaled force field
accurately reproduced RDFs from ab initio MD simulations.
2017-11-07 00:00:00
BF
dynamic
density
surface tensions
Radial distribution functions
OPLS-AA parameters
theory Comput
OPLS -2009IL force field parameters
Δ H vap
Monte Carlo
Revisiting OPLS Force Field Parameters
surface tension
PF
vaporization
bi
interaction
force field
Ionic Liquid Simulations
diffusion coefficients
sampling technique
heat capacities
charge transfer effects
RDF
choline cations
ab initio MD simulations
1- alkyl -3-methylimidazolium
Experimental validation
OPLS -2009IL parameters
RMIM