BARRIERS, THRESHOLDS, AND RESONANCES - SPECTRAL QUANTIZATION OF THE TRANSITION-STATE FOR THE COLLINEAR D+H-2 REACTION

We have analyzed the quantum dynamics of the collinear D+H2 reaction in the region of the transition state on the DMBE potential energy surface. Using the spectral quantization method, the dynamical features of the transition state are mapped out through a sequence of hypothetical Franck-Condon spectra. These spectra are generated by time-dependent wave packet dynamics. A comprehensive analysis of the spectra has revealed three distinct classes of peaks associated with (1) conventional reactive resonances, (2) threshold anomalies, and (3) barrier resonances. Individual peaks in the spectra are assigned through the use of time-independent wave functions which are obtained by Fourier transformation of the wave packet at the peak energies. The positions, lifetimes, and wave functions are extracted for all 23 conventional and barrier resonances. A new analytic line shape formula is developed to fit the spectral peaks of the barrier resonances. The exact quantum analysis is also supplemented with a semiclassical treatment based on periodic orbits. Most of the resonance states are found to be associated with single quantized periodic orbits in the transition state region. © 1995 American Institute of Physics.