The values of the Coulomb coupling are also compared with the couplings derived from the supermolecular calculation of a dimer using the doubled active space. Coulomb coupling is obtained as half of the splitting of the corresponding excited dimeric states. Note that in this case the coupling implicitly includes the effect of exchange and charge transfer between monomers and can be compared to the direct Coulomb coupling only with caution, especially for short distances. The strong interaction of monomers at |R mn | < 3 Å for the S 0 →S 1 transition and at |R mn | < 4 Å for the S 0 → S 2 transition prevents one from identifying corresponding states since the respective dominating electronic configurations cannot be found in any of the calculated wave functions. However, for distances larger than 4 Å, in both cases, one observes an agreement between the result of the implemented protocol and the supermolecular calculation (cf. Ref. 16).