Condensed Matter Physics, 2012, vol. 15, No. 2, p. 23801:1-10
On the contact values of the density profiles in an electric double layer using density functional theory
(Laboratory of Theoretical Physics, Department of Physics, University of Puerto Rico, Box 70377, San Juan, Puerto Rico 00936-8377, USA)
(Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602-5700, USA)
(Department for the Modelling of Physico-Chemical Processes, Faculty of Chemistry, MCSU, 20031 Lublin, Poland)
A recently proposed local second contact value theorem [Henderson D., Boda D., J. Electroanal. Chem., 2005, 582, 16] for the charge profile of an electric double layer is used in conjunction with the existing Monte Carlo data from the literature to assess the contact behavior of the electrode-ion distributions predicted by the density functional theory. The results for the contact values of the co- and counterion distributions and their product are obtained for the symmetric valency, restricted primitive model planar double layer for a range of electrolyte concentrations and temperatures. Overall, the theoretical results satisfy the second contact value theorem reasonably well, the agreement with the simulations being semi-quantitative or better. The product of the co- and counterion contact values as a function of the electrode surface charge density is qualitative with the simulations with increasing deviations at higher concentrations.
electric double layer, restricted primitive model, density profiles
82.45.Fk, 61.20.Qg, 82.45.Gj