Please use this identifier to cite or link to this item:
Title: Solvent separated sodium chloride ion pairs in a water-DMSO mixture: Friction kernels and transmission coefficients
Authors: DAS, AK
Keywords: Constrained Molecular-Dynamics
Equilibrium Solvation Dynamics
Mean Force
Dependent Friction
Issue Date: 1998
Citation: JOURNAL OF MOLECULAR LIQUIDS, 77(1-3), 131-156
Abstract: In a mixed solvent of water and dimethyl sulphoxide (DMSO) (with a mole fraction of DMSO = 0.21), the solute sodium chloride forms two distinct solvent separated ion pair (SSIP) species at interionic separations of 5.4 Angstrom and 7.1 Angstrom respectively. These SSIPs are separated by a free energy barrier at 6.6 Angstrom. Molecular Dynamics (MD) simulations are performed on the ion pair in the presence of the mixed solvent to study the solvation structure and the solvation dynamics through the friction kernels. The structural studies bring out the gradual evolution of the solvation of the individual ions as the interionic separation is increased and also the influence of both the components of the solvent mixture. The solvation shell of the ion pair has dominant contribution from water at all the three separations. Analysis of the computed normalised friction kernels of the ion pair at ion-ion separations of 5.4 Angstrom. (SSIP1), 6.6 Angstrom (TS) and at 7.1 Angstrom (SSIP2) reveals that the relative contribution to the net solvent friction by the individual solvents are different at these interionic distances. At all the ion-ion separations, the net dynamic friction experienced by the ion pair in the presence of the mixed solvent is similar to that in water. Intersolvent cross-correlated frictions on the ion pair are negative at short times and decay to zero within 0.7 ps. The dynamics of the barrier crossing reaction has also been studied using the Kramers and Grote-Hynes (GH) theories. The magnitude of the barrier frequency in the mixed solvent is larger than the corresponding barrier frequencies in water as well as in DMSO. The GH transmission coefficient approximately matches with the transmission coefficient obtained by the direct MD simulations. (C) 1998
ISSN: 0167-7322
Appears in Collections:Article

Files in This Item:
There are no files associated with this item.

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.