Ion Distribution in an Isolated Charged NanoSpherical Cavity: A DFT Study

In this paper, we present a perturbative density functional theory (DFT) in cooperate by perturbation theory for describing the density profiles of negative and positive ions in an isolated spherical cavity that there is a steady charge on it. A density-functional theory is used on the framework of the restricted primitive model that the ions have same size and the solvent is represented 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 ions increases with Q, for example, at a concentration of 1 M, monovalent ions in the cavity whit radius of coions is not seen against counterions, but mean electrostatic potential is still positive. Moreover by increasing the surface charge on the surface of spherical pore, the two species are separated from each other. Obviously, as the surface charge is higher, the counterions are more entrained until the distribution of the ions is restricted to the counterions.