INTEGRAL-EQUATION THEORY FOR THE ELECTRODE-ELECTROLYTE INTERFACE WITHTHE CENTRAL FORCE WATER MODEL - RESULTS FOR AN AQUEOUS-SOLUTION OF SODIUM-CHLORIDE
M. Vossen et F. Forstmann, INTEGRAL-EQUATION THEORY FOR THE ELECTRODE-ELECTROLYTE INTERFACE WITHTHE CENTRAL FORCE WATER MODEL - RESULTS FOR AN AQUEOUS-SOLUTION OF SODIUM-CHLORIDE, Molecular physics, 86(6), 1995, pp. 1493-1516
The structure of an aqueous solution of sodium chloride at a planar su
rface is investigated by integral equation techniques. With the centra
l force water model the aqueous electrolyte is modelled as a mixture o
f sodium and chloride ions, and partially charged hydrogen and oxygen
atoms interacting via effective spherically symmetric pair potentials.
The correlation functions obtained from the Ornstein-Zernike equation
with reference hypernetted chain closure give a good description of t
he bulk structure (e.g., hydrogen bonded water network, solvation shel
l). With the bulk information and the Wertheim-Lovett-Mou-Buff equatio
n we have calculated the density profiles at the uncharged and charged
surfaces. The rather rigid ice-like water structure found previously
at the neutral surface strongly repels the ions. Steric interactions b
etween the ions of different sizes and the ice-like water structure do
minate the ionic distribution near the surface. This model electrolyte
also responds differently to opposite charges on the surface. We foun
d the asymmetry in the differential capacitance curve determined entir
ely by the response of the interfacial water structure.