The quantity ρ iter (r) is updated iteratively in solving eq. 16 for a fixed solute charge density (ρ sol ), the latter of which is obtained via self-consistent field (SCF) iterations. For the permittivity function in eq. 1 that forms the basis of PCM theory, the factor [1 -ε(r)]/ε(r) in eq. 18 vanishes inside of the solute cavity. Following iterative solution of eq. 16, the polarization density is used to augment the one-electron contributions to the solute's Fock operator, to include the interaction between ρ sol (r) and ρ pol (r). The total energy is