Fast mode frequency, hydrogen bonds

The cornerstone of the strong anharmonic coupling theory relies on the assumption of a modulation of the fast mode frequency by the intermonomer distance. This behavior is correlated by many experimental observations, and it is undoubtly one of the main mechanisms that take place in a hydrogen bond. Because the intermonomer distance is, in the quantum model, represented by the dimensionless position coordinate Q of the slow mode, the effective angular frequency of the fast mode may be written [52,53]... 

Based on isotopic substitution, a low-frequency band with a maximum around 100 cm" in liquid amides and proteins is assigned to a mode involving motions of atoms in the hydrogen bonds. This motion can drive the making or breaking of hydrogen bonds in amides and proteins and this mode is an example of how a fast dynamical mode can drive a conformational change of a biomolecule. 

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