THE EXTRACTION OF DYNAMICS AND THE CLASSICAL MECHANICAL SIMULATION OF LOW RESOLUTION REGULAR AND CHAOTIC SPECTRA - HCN/HNC

The classical analog of the quantum survival probability function as well as low resolution spectra are calculated for HCN and its isomer HNC, and compared with available experimental ones and with the recent quantum mechanical SEP spectra obtained by Wyatt and co-workers for energies up to about 30 000 cm-1. The HCN(0,v,0)A 1A″ → X 1Σ+ with the bending quantum number v = 0-3, and the corresponding HNC (0,0,0) transitions were studied. It is shown that classical mechanics satisfactorily reproduces the main features of the survival probability functions and illustrates the dynamics, the results of which are the spectra. Specifically the observed spectral features are associated with the regular or chaotic motion localized in particular resonance zones. The spectroscopic agreement between classical and quantum mechanics reveals that there should be a correspondence between the regions of phase space where the classical motion is localized and the excited quantum eigenfunctions determining the SEP spectra. These results show that the computationally simple and pictorial classical mechanical techniques used here offer readily available means for extracting the dynamics from highly excited molecular spectra. © 1990 American Institute of Physics.