Interaction of vibrations and rotations; polyads and their spectra

In this Chapter we will consider with the help of a model Hamiltonian the interaction of vibrations and rotations. It will be shown, that this interaction leads to the strengthening of localization. This is due to the fact, that in this case, along with the tunneling of the vibrational excitation, the tunneling of the vector of momentum J with respect to the body frame is required “flip-flop”. This last process is very slow for large values of J and J k — flip-flops for fast rotation are prohibited.