Molecular Dynamics of Chemical Reactions in Solution

We hope to answer one of the most fundamental and important unsolved questionsin chemistry: how, from a molecular perspective, do chemical reactions in solutionactually occur. The key to solving this long-standing problem is to understand themolecular dynamics, i.e., the motions of the atoms and the forces that drive them. Wehave already developed theoretical techniques and computational procedures involvingspecialized computer hardware needed to calculate the molecular dynamics for manychemical reactions in solution. From the dynamics we have derived the interface forexperimental verification, namely transient electronic, infrared, and Raman spectra aswell as X-ray diffraction, all of which are potentially observable manifestations of theatomic motions during the reaction. We have tested our approach on the simpleinorganic I 2 photodissociation and solvent caging reaction. The agreement betweenmolecular dynamics based theory and experimental picosecond transient electronicabsorption spectrum as a function of solvent, time, and wavelength is sufficiently closeas to indicate that for the first time we are discovering at least part of the moleculardynamics by which a real solution chemical reaction takes place.