A model for the electrical double layer combining integral equation techniques with quantum density functional theory

We have complemented the singlet reference interaction site model for the electric double layer by quantum chemical calculations for the interaction of ions and solvents with an electrode. Specific calculations have been performed for an aqueous solution of NaCl in contact with a Ag(1 1 1) electrode. The particle profiles near the electrode show the specific adsorption of Cl− ions, but not of Na+, and are at least in qualitative agreement with those obtained by molecular dynamics. Including the electronic response of the silver surface into the model results in reasonable capacity–charge characteristics.

• We augment a double-layer model based on integral equations by calculating the interaction parameters with the electrode from quantum density functional theory
• Explicit model calculations for Ag(1 1 1) in aqueous solutions give at least qualitatively good results for the particle profiles
• Ours is the only method which allows the calculation of capacity–charge characteristics.
• We obtain reasonable values for the Helmholtz (inner-layer) capacity.