in which ρ sol (r) is the charge density of the atomistic solute, obtained herein from a quantum chemistry calculation, and ϕ tot (r) is the total electrostatic potential. The latter includes the potential generated by ρ sol (r) but also contributions from polarizing the continuum. Gaussian electrostatic units are used in eq. 2, such that 4πε 0 = 1. The original PCM solves the model problem defined by by eq. 2 and the sharp dielectric interface in eq. 1, where r ∈ Ω in eq. 1 indicates the interior of the molecular cavity (see Fig. ) and ε s is the (static) dielectric constant of the solvent. In the special case where ρ sol (r) vanishes for r /