Simulation of ion recombination in low permittivity solvents: Extended clusters

Ion recombination in spatially extended multi-pair cation-anion (C⁺/A^-) and cation-electron (C⁺/e^-) systems in low permittivity solvents has been modeled using random flights simulation and the independent reaction times method, in order to investigate the effects of the spatial distribution of the reactants on the recombination kinetics. The kinetics are found to depend on the separations between adjacent C⁺s, the C⁺-C⁺-C⁺ angle, and the cation and anion diffusion coefficients. The long-time yields predicted by the two simulation methods are in good agreement, however, the short-time dependence of the decay kinetics simulated by the IRT model is slower than that of the more realistic random flights method when the inter-cation distances are small, because of the cumulative effects of the Coulomb inter-ion forces. Some other small and subtle effects of initial distribution are presented, which are not recognized by the IRT method.