  In this study the Singlet Reference Interaction Site Model (SRISM) is
employed to the study of the electrode charge dependence of the capacitance of
a planar electric double layer using the primitive model of the double layer
for a high density electrolyte that mimics an ionic liquid. The ions are
represented by charged hard spheres and the electrode is a uniformly charged
flat surface. The capacitance of this model fluid is calculated with the SRISM
approach with closures based on the hypernetted chain (HNC) and
Kovalenko-Hirata (KH) closures and compared with simulations. As long as the
magnitude of the electrode charge is not too great, the HNC closure shows the
most promise. The KH results are reasonably good for a high density electrolyte
but are poor when applied at low densities.
