Proton-phonon coupling

C. Can Coherent Tunneling of Heavy Particles Be More Probable than That of Light Particles The Role of Proton—Phonon Coupling... 

Thus, the proton-phonon coupling being inserted into the initial Hamiltonian is able to suppress or enlarge the coherent tunnel repolarization of the chain. The realization of this or that option depends not only on the spin-phonon interaction, but also on the form of the two-well potential of the hydrogen bond. 

The interconversion of the two tautomer forms of dimers (Fig. 2) by a concerted two proton transfer is governed by a double-well potential. In condensed phases the two possible tautomers are identical. Skinner and Trommsdorff [21 ] treated a model of crystalline benzoic acids in which the dynamics of each proton pair is uncorrelated with other pairs. Their model was based on a single doubleminimum potential coupled to a thermal bath—that is, crystal vibrations. It was believed that in a condensed phase the crystal field breaks the symmetry of the two wells (Fig. 3). If Fig. 3 indeed represents the real situation when the proton transfer from the left well to the right one should take place at the participation of vibrations of the crystal that is, phonons of some sort should activate the proton transfer. We would like to emphasize that this is the conventional viewpoint, which is widely employed by physicists. 

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