A systematic Monte Carlo simulation study of the primitive model electrical double layer over an extended range of concentrations, electrode charges, cation diameters and valences

Abstract: The purpose of this study is to provide data for the primitive model of the electrical double layer, where ions are modeled as charged hard spheres, the solvent as an implicit dielectric background (with dielectric constant $\epsilon= 78.5$), and the electrode as a smooth, uniformly charged, hard wall. We use canonical and Grand Canonical Monte Carlo simulations to compute the concentration profiles, from which the electric field and electrostatic potential profiles are obtained by solving Poisson's equation. We report data for an extended range of parameters including 1:1, 2:1, and 3:1 electrolytes at concentrations $c=0.0001-1$ M near electrodes carrying surface charges up to $\sigma=\pm 0.5$ Cm$^{-2}$. The anions are monovalent with a fixed diameter $d_{-}=3$ {\AA}, while the charge and diameter of cations are varied in the range $z_{+}=1$, 2, 3 and $d_{+}=1.5$, 3, 6, and 9 {\AA} (the temperature is $298.15$ K). We provide all the raw data in the Supporting Information.