Intramolecular relaxation of vibrations in the presence of local modes

Abstract

In the previous Chapters it has been shown that, if the molecule possesses equivalent (degenerate) vibrational modes (such as several C — H bonds, for example), the nonlinearity of intramolecular vibrations leads to the appearance of Local Modes (LM) and to highly pronounced clusterization of vibrational levels. The same applies to the rotational evolution (motion) of the molecule, as rotations are governed by a nonlinear Hamiltonian. The rotational levels group into clusters of two or more ones, depending on the point symmetry of the effective Hamiltonian for rotations H(J). The same is true for the rotational - vibrational states in the case of degeneracy of the vibrational level.