This project in the Theoretical and Computational Chemistry program concerns exact quantum theoretical calculations of the dynamics, spectroscopy and photochemistry of highly excited molecules. These studies will be of direct importance in relating experimental observables to detailed molecular properties, including the accurate description of high energy vibrational modes, the assignment of vibrational spectra in terms of these modes, the analysis of predissociative spectra in terms of state-specific unimolecular reaction, and the preparation of excited molecules with ultrafast pulsed lasers. Vibrational modes of high energy will be studied both by simple approximate methods such as self-consistent field techniques and by exact variational calculations. Extended versions of the complex coordinate method will be used to study vibrational predissociative resonances for determination of the molecular couplings and dynamics whcih govern the unimolecular lifetime. Intramolecular vibrational resonances in molecules with high state densities will be studied by an optical potential technique to characterize the high energy states prepared by pulsed lasers. The dynamics of such states will also be calculated to reveal the spectroscopic consequences of the competition of state preparation with unimolecular dynamics.
