Dimeric Formic Acid and Related Dimers

Earlier, Shida et al. [41] concluded, on the basis of MCSCF calculations, that in addition to the synchronous path, an asynchronous pathway appeared if the inter- 

The other dimers in Fig. 29.7 show asymmetry. If the proton transfer potential is asymmetric, there will be no synchronous transfer and at most accidental level splittings. In the formamide dimer [44] the two hydrogen bonds are the same but the donor and acceptor groups are different. The available calculations indicate that the structure of the equilibrium configuration is intermediate between the equilibrium configurations of dimeric formic acid and dimeric formamidine, as 

With one exception, these results are based solely on quantum-chemical calculations of the potential energy surface. Theoretical evaluation of the transfer dynamics has been attempted only for the formic acid dimer, for which two general level splittings have been observed and assigned to synchronous double proton tunneling in the ground state and a vibrational excited state, respectively. 

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