COMPETITIVE ELECTRON TRANSFERS IN MODEL TRIAD SYSTEMS - MD SIMULATIONS

The charge separation reactions for model systems containing an electr on donor, D, and two electron accepters, A, in acetonitrile solvent at room temperature have been investigated. The electron transfer rate c onstants for A1-D-A2 and D-A1-A2 systems with various angular arrangem ents of the subunits are expressed in terms of the two-dimensional sta tistical distributions of the reaction coordinates, which are defined as the electrostatic potential difference between the respective pair of the reacting sites. These distributions have been evaluated by the MD computer simulation method. The dependence of the charge separation rate constant on the spatial arrangement of the subunits of the triad system, which arises from the present calculations, has been compared with the corresponding result obtained on the basis of the dielectric continuum model of the solvent. The dynamics of the reaction coordina tes for both model systems has been characterized by the classical tim e autocorrelation and cross-correlation functions.