Solvation dynamics in a Brownian dipole lattice: A comparison between theory and computer simulation

Papazyan and Maroncelli [J. Chem. Phys. 95, 9219 (1991)] recently reported computer simulations of solvation dynamics of an ion in a Brownian dipole lattice solvent. In the present article we compare these results to predictions of a number of theories of solvation dynamics in the diffusive limit. The frequency-dependent dielectric response functions needed as input to many of the theories are derived from further simulations of the lattice solvent [H. X. Zhou and B. Bagchi, J. Chem. Phys. 97, 3610 ( 1992)]. When properly applied, all of the currently popular molecular theories yield reasonable predictions for the time scale of the solvation response. The dynamical MSA model [P. G. Wolynes, J. Chem. Phys. 86, 5133 (1987)] and the memory function theory of Fried and Mukamel [J. Chem. Phys. 93, 932 ( 1990)] both provide nearly quantitative agreement with all aspects of the solvation dynamics observed in these simulations.