ION SOLVATION FROM ISOELECTRONIC PROCESSES AT THE NUCLEUS

A Kohn-Sham (KS) like formalism for the calculation of solvation energ ies of singly charged ions is presented. The approximate theory is bas ed on a simple model that represents embedding an atomic ion into a po larizable liquid. through successive isoelectronic processes at its nu cleus. In this way, the controversial procedure of selecting appropria te ionic radii, as involved in the computation of solvation energies v ia the Born formula, is avoided and replaced by energy changes involvi ng a varying nuclear charge. The effective KS potential is derived wit hin the framework of a linear response model. It is written in terms o f the electrostatic potential at the nucleus of an auxiliary transitio n state pseudo-atom, and the electron density induced by the electrost atic external perturbation. As an illustration, the formalism was impl emented within the Hartree-Fock-Slater Xalpha approximation. This is d iscussed in detail.