and in the somewhat larger (naphthalene) 2 , whose CT states have also received attention. Both dimers are arranged in a parallel face-to-face orientation. Solvation corrections for singlet CT from C 2 H 4 to C 2 F 4 , and from one naphthalene monomer to the other, are shown in Fig. as a function of reciprocal intermolecular separation, 1/R. The quantity plotted is the difference between excitation energies computed using ε 0 = 78.4 versus ε 0 = 1.0, i.e., the solvent shift in water. RAS-SF calculations on C 2 H 4 • • • C 2 F 4 use the cc-pVTZ basis set and RIMP2-cc-pVTZ auxiliary basis set while those on (naphthalene) 2 use the 6-31G* basis set and RIMP2-cc-pVDZ basis set.