QUANTUM CHAOS IN COLLINEAR (HE,H-2(+)) COLLISIONS

The quasibound spectrum of the transition state in collinear (He, H-2( +)) collisions is obtained from. time-dependent wave packet calculatio ns. Examination of short- and long-range correlations in the eigenvalu e spectra through a study of the nearest neighbor spacing distribution , P(s), and the spectral rigidity, Delta(3)(L), reveals signatures of quantum chaotic behavior. Analysis in the time domain is carried out b y computing the survival probability [[P(t)]] averaged over initial st ates and Hamiltonian. All these indicators show intermediate behavior between regular and chaotic. A quantitative comparison of [[P(t)]] wit h the results of random matrix theory provides an estimate of the frac tion of phase space exhibiting chaotic behavior, in reasonable agreeme nt with the classical dynamics. We also analyse the dynamical evolutio n of coherent Gaussian wave packets located initially in different reg ions of phase space and compute the survival probability, power spectr um and the volume of phase space over which the wave packet spreads an d illustrate the different behaviors. (C) 1996 American Institute of P hysics.