Periodic motions due to nonlinearity: the regular vibrational dynamics of chaotic DCN

Periodic motions due to nonlinear resonances of D-C and C-N stretches of DCN molecule are shown by an algorithm based on coset representatives. These motions are highly localized on either D-C or C-N bond, or that their action ratios on D-C and C-N are 2:3 or 1:1. These periodic motions bear peculiar characters not possessed by the normal modes based on the harmonic approximation. It is shown that chaotic motion is mainly due to the D-C stretch. However, quasiperiodic modes of highly localized D-C stretch are also identified.