DEPHASING OF A SOLVATED 2-LEVEL SYSTEM - A SEMICLASSICAL APPROACH FORPARALLEL COMPUTING

The statically broadened vibronic line shape of a molecular solute in a liquid solution may be computed from a knowledge of the equilibrium structure of the fluid. By contrast, calculation of the contribution o f solvent nuclear motions to this lineshape requires the use of semicl assical mechanics. Liquid-state electronic spectra have previously bee n calculated with a semiclassical approach relating the Line shape to fluctuations in the electronic energy gap as the fluid evolves classic ally on the ground-state potential surface. We propose an alternative formulation that incorporates dynamics on both the ground-state and ex cited-state surfaces. While more computationally intensive, this appro ach lends itself readily to parallel computation. Line shapes using bo th methods are computed for a Lennard-Jones solute in a Lennard-Jones solvent, for which the depth of the potential well characterizing solu te-solvent interactions changes with electronic state. (C) 1996 Americ an Institute of Physics.