CORRELATION-FUNCTION DIAGNOSIS OF CHAOTIC VIBRATIONS IN HCN

Classical trajectory calculations on the potential energy surface of Murrell, Carter, and Halonen have been performed from semiclassical starting conditions between the zero-point energy and dissociation. Diagnosis of the onset of classical chaos has been accomplished in several ways, but especially by using as a criterion the amplitude of the four-mode instantaneous correlation function. The onset of chaos occurs first in the bending mode, at approximately 11 000 cm-1. At the dissociation limit, virtually all trajectories starting from overtones of the bend are chaotic within 41 ps of the start of the trajectory. On the other hand, the corresponding threshold when overtones of the stretching vibrations are initially excited is near 26 000 cm-1, and only a fraction of those trajectories just below dissociation become chaotic. © 1990 American Chemical Society.