If one considers a dimer interaction in the Kasha model, we recall that as two quantum bodies come closer together, the localised energy levels begin to diverge aggressively. In addition to Frenkel states, strong charge transfer states enter into the energetic continuum; as well charge transfer interactions interfere with the vibronic coupling between two electronic states. In this regime, the coupling may not always be weak; therefore perturbation methods may not be valid. As such, dimer interactions are nontrivial, and alternative quantum methods need to be considered.