In the Generalized Mulliken-Hush (GMH) approach to diabatization, 18,33 the adabatic-todiabatic transformation is based on the definition of the diabatic states as eigenstates of the dipole moment. Specifically in a two-state model, the method requires the calculation of the dipole moment of each adiabatic state µ 1 and µ 1 , and the transition dipole moment between the two, µ 12 . The non-adabatic coupling element is then calculated as