| The theory of active control of molecular motion in two-state, three-state and n-state systems by use of shaped laser pulses is developed, emphasizing the role of interference. Examination of the characteristics of population and energy flow from one surface to another shows that the phase of the radiation is the active control parameter. We also show how the control of the dynamics of an n-state system can be represented in terms of the control of the dynamics of a precisely defined surrogate fewer state system. As an example of real molecular control, we investigate the control of the branching between photodissociation products and the control of wave packet localization in femtosecond pump pulse excitation of NaI.; This work also reports the results of applying the complex scaling method to the study of the vibrational predissociation of the weakly bound van der Waals molecule HeI{dollar}sb2{dollar}. The reaction rate constants are calculated from the stationary point (resonance state) of the {dollar}Theta{dollar}-trajectory of the imaginary part of the complex energy. We also show that the common belief--that {dollar}Theta{dollar}-trajectories of both real and imaginary parts of the complex energy should display stationary behavior at the same scaling angle is not correct. We propose a new method to decouple Fermi resonant wave functions to zero order vibrational wave functions, which helps to resolve the complication introduced by Fermi resonance in analyzing assignments on polyatomic vibrational spectra.; In the last part we report the calculation results of the rate constants for the isomerization reactions of HCN {dollar}leftrightarrow{dollar} CNH and cyclobutanone using an elegant classical theory of unimolecular reaction rate developed by Rice et al. (DGRZ). In both cases we find that the rate constants from DGRZ calculations are in reasonable agreement with those obtained from trajectory calculations. |
