Solvent effects on electronic spectra studied by multiconfigurational perturbation theory

The complete active space (CAS) self-consistent field (SCF) method combined with multiconfigurational second-order perturbation theory (CASPT2) and a self-consistent reaction field (SCRF) model is used to study the effect of solvation on excited states of different molecules such as acetone, pyrimidine, some aminobenzene derivatives, indole, and imidazole. The present SCRF model, in which the solute molecule is placed into a spherical cavity surrounded by a dielectric continuum, also includes a repulsive potential representing the solute–solvent exchange repulsion and considers the time dependence of the absorption process. In general, we find that our calculations do reproduce the trends observed in experiment but underestimate the solvatochromic shifts.