An MD Study of the Applicability of the Walden Rule and the Nernst- Einstein Model for Ionic Liquids
HJ Liu and E Maginn, CHEMPHYSCHEM, 13, 1701-1707 (2012).
Six different ionic liquids containing imidazolium, pyrrolidinium and ammonium cations paired with bis(trifluoromethyl)sulfonylimide and bis(perfluoroethyl)sulfonylimide anions were studied using molecular dynamics simulations. Ionic conductivities, shear viscosities and self- diffusivities were computed and compared to see what relationships exist between these three transport properties. The simulations suggest that these ionic liquids follow closely the Walden rule, which relates ionic conductivity to fluidity. The computed ionic conductivities agree well with those predicted from the NernstEinstein model, suggesting that long-time correlation among ion velocities is small, or that the ionicity of these ionic liquids is high.
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