Angstrom scale processes

If all of the atoms and charges in the system of interest are explicitly represented and atomic polarization is included, the use of a dielectric constant other than unity would be inappropriate. A variety of models has been used, however, to approximate the dielectric behavior of a macromolecular system where the solvent was not explicitly included. Dielectric constants for the protein interior between 2 and 10 have been employed, as has a distance-dependent dielectric response equal to the distance in angstroms.78 Also, simple forms of the Kirkwood-Westheimer-Tanford model79 have been used to approximate the effect of the aqueous solvent. An approach that may improve our understanding in this area employs linear response theory to evaluate the spatially dependent dielectric response.80 In any such model it is necessary to consider the frequency dependence of the dielectric constant relative to the time scale of the dynamic process under consideration. 

How do chemical reactions happen in solution What are the microscopic processes that lead to a thermal reaction system s climbing a barrier, reaching a transition state, choosing whether or not to go on to products, and then coming back down to equilibrium How does nonthermal activation, such as in photodissociation, change this picture and what other processes are important in such reactions How can we look in detail at these processes, both on the appropriate (angstrom) length scale and (femtosecond/picosecond) time scale ... 

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