With this grant in the Theoretical and Computational Chemistry Program of the Chemistry division, Professor Coalson will develop wavepacket methods for computing the dynamical evolution of quantum many-body systems and will apply these methods to several problems in condensed phase spectroscopy. The computations will aid in the understanding of rate processes in these systems which explicitly depend on quantum effects. The problems to be investigated will include: photodesorption cross sections of molecular adsorbates (e.g., CH3Br and NO), and resonance raman excitation profiles of the bovine pancreatic tripsin inhibitor protein. The principle technique to be employed is the time-dependent Hartree grid method which involves factorization of the complete many-body system wave function into low dimensional pieces for various subsystems. This approximation is suitable for treating subpicosecond dynamics as required in the above applications. In order to treat longer time processes, accuracy beyond the Hartee level will be necessary. The principal investigator will develop algorithms to do configuration interaction in conjunction with the time-dependent Hartee grid solutions. These algorithms will introduce direct correlation between wavepackets representing the various subsystems into which the overall system has been partitioned.