Vertical electronic excitation with a dielectric continuum model of solvation including volume polarization. I. Theory

A dielectric continuum model of solvation is developed for use in conjunction with electronic structure calculation on vertical electronic excitation of a solute. Particular attention is paid to volume polarization arising from quantum mechanical penetration of solute charge density outside the cavity that nominally encloses it, which affects both the fast and slow components of the dielectric response. An approximation that closely simulates volume polarization while being easier to implement in practice is also described. These approaches are compared to other related formulations found in the literature.