This correction was added to deal with Rydberg-type excited states, where the Coulomb integral is small. (For cases of orbital degeneracy it is suggested to average J over the degenerate configurations to avoid symmetry breaking, 9 but our implementation does not do this.) In addition to c 1 = 0.317, parameters c 2 = 0.033 E h and c 3 = 1.27 × 10 7 E h in Eq. ( ) were determined by Grimme, 9 specifically for use with the B3LYP functional. Grimme's implementation also uses a custom basis set that is described in Section III C. The DFT/ CIS method is intended as a semi-empirical approach that is tied specifically to this one particular XC functional and basis set.