Communication: Kinetic and pairing contributions in the dielectric spectra of electrolyte solutions

In the late 1970s, Hubbard and Onsager predicted that adding salt to a polar solution would result in a reduced dielectric permittivity that arises from the unexpected tendency of solvent dipoles to align opposite to the applied field. Here we develop a novel non-equilibrium molecular dynamics simul...

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Bibliographic Details
Published in:The Journal of chemical physics 2014-06, Vol.140 (21), p.211101-211101
Main Authors: Sega, M, Kantorovich, S S, Holm, C, Arnold, A
Format: Article
Language:English
Subjects:
Chlorine Compounds - chemistry
Electrolytes - chemistry
Kinetics
Molecular Dynamics Simulation
Potassium - chemistry
Salts - chemistry
Sodium - chemistry
Solutions - chemistry
Solvents - chemistry
Thermodynamics
Water - chemistry
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Summary:In the late 1970s, Hubbard and Onsager predicted that adding salt to a polar solution would result in a reduced dielectric permittivity that arises from the unexpected tendency of solvent dipoles to align opposite to the applied field. Here we develop a novel non-equilibrium molecular dynamics simulation approach to determine this decrement accurately. Using a thermodynamic consistent all-atom force field we show that for an aqueous solution containing sodium chloride around 4.8 mol/l, this effect accounts for 12% of the total dielectric permittivity. The dielectric decrement can be strikingly different if a less accurate force field for the ions is used. Using the widespread GROMOS parameters, we observe in fact an increment of the dielectric permittivity rather than a decrement, caused by ion pairing and introduced by a too low dispersion force.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.4880237