3-DIMENSIONAL QUANTUM DYNAMICS STUDY OF VIBRATIONAL PREDISSOCIATION OF HEI2 VAN-DER-WAALS MOLECULE FOR LOW VIBRATIONAL-EXCITATION USING THETIME-DEPENDENT WAVE-PACKET METHOD

Three-dimensional quantum mechanical calculations for vibrational pred issociation of HeI2(B) van der Waals molecules are presented using the time-dependent wave packet technique within the golden rule approxima tion. The total and partial decay widths, lifetimes, rates and their d ependence on initial vibrational states were obtained for HeI2 at low initial vibrational excited levels. Our calculations show that the cal culated total decay widths, lifetimes and rates agree well with those extrapolated from experimental data available. The predicted total dec ay widths as a function of initial vibrational states exhibit highly n onlinear behavior. The very short propagation time (less than 1 ps) re quired in the golden rule wave packet calculation is determined by the duration time of the final state interaction between the fragments on the vibrationally deexcited adiabatic potential surface. The final st ate interaction between the fragments is shown to play an important ro le in determining the final rotational distribution. This interpretati on clearly explains the dynamical effect that the final rotational dis tribution shifts to the lower rotational energy levels as the initial vibrational quantum number upsilon increases.