About the coupling between librational motions and conformational transitions in chain molecules

The conformational transitions lead to reorientations of a small fraction only of a chain molecule. This follows from the analysis of the barrier crossing problem according to the Kramers theory. Therefore, the librational motion operating after a transition is responsible for the attainment of the new equilibrium distribution. A simplified treatment is presented for the model system of an infinite chain of rotors. It is shown that the reorientations of the chain units induced by a conformational transition, propagate along the chain with increasing time delays. This constitutes an effective mechanism of coupling between the librational motion and the conformational dynamics in long chain molecules.