Ion Distribution in an Isolated Charged Nano Spherical Cavity: A DFT Study

In this paper, we present a perturbative density functional theory (DFT) in cooperate byperturbation theory for describing the density profiles of negative and positive ions in an isolatedspherical cavity that there is a steady charge on it. A density-functional theory is used on theframework of the restricted primitive model that the ions have same size and the solvent isrepresented by a dielectric continuum [1].According to the results the density of ion and also the mean electrostatic potential increase,with increasing surface charge Q. Also, the difference between the positive and negative ionsincreases with Q, for example, at a concentration of 1 M, monovalent ions in the cavity withradius of R/σ=1.5, coions is not seen against counterions, but mean electrostatic potential isstill positive. Moreover by increasing the surface charge on the surface of spherical pore, the twospecies are separated from each other. Obviously, as the surface charge is higher, the counterionsare more entrained until the distribution of the ions is restricted to the counterions.

Keywords:

DFT , Isolated Charged Spherical Cavity , Ion Distribution