Fig. presents a different kind of modification of the ground state polariton potential. The parameters for model II are picked such that the covalent state |C lies energetically higher than the |D and |A states. Thus, the ground adiabatic state is largely composed of |D and |A states hybridized through the diabatic coupling V DA . As shown in Fig. , the electron density no longer follows along with the proton, especially in the middle panels of Fig. for R ≈ 0, in contrast to those in Fig. . Instead, the charge density tunnels from the donor to the acceptor ion, as the ground adiabatic state sharply changes its character from |D to the |A state near R ≈ 0. This model can be regarded as an example of a non-adiabatic proton coupled electron transfer (PCET) reaction. Note that the permanent dipoles presented in Fig. are visually similar to the permanent dipoles shown in Fig. for model I, as the underlying nature of the MH diabats |D , |A and |C are the same in both models.