Polar solvation dynamics: A combination of the reference interaction-site model and mode-coupling theories

Abstract

We employ the reference interaction-site model (RISM) theory for solvation dynamics of simple ions in acetonitrile. For the description of time evolution of solvent relaxation, we apply the mode-coupling theory recently developed by Yamaguchi and coworkers [Mol. Phys. 101, 1211 (2003)]. The combination of the RISM/mode-coupling theory is used for the calculation of the dynamic response function, SS(t), which measures the relaxation of average energy of the solute-solvent system. SS(t) decays with the Gaussian plus under-damped curves in the time duration of first 1 ps, followed by slow, long-tailed components down to tens of picoseconds. We show that the RISM/mode-coupling framework is applicable rather well for the detailed description of solvation dynamics at the molecular level.