Independence of the rate of the hot charge recombination in excited donor-acceptor complexes from the spectral density of high-frequency vibrations

Ultrafast non-thermal charge recombination dynamics in excited donor-acceptor complexes are theoretically investigated in the framework of the stochastic point-transition model. The medium reorganization is treated as non-Markovian. For the description of the reorganization of intramolecular high-frequency vibrational modes real spectral densities are exploited. The results of simulations indicate that the ultrafast charge recombination dynamics are practically invariant with respect to high-frequency vibrational spectrum provided the total reorganization energy of these modes is fixed and the mode number is no less than 5.