INFLUENCE OF MOLECULAR-REORIENTATION ON ELECTRONIC-ENERGY TRANSFER BETWEEN A PAIR OF MOBILE CHROMOPHORES - THE STOCHASTIC LIOVILLE EQUATIONCOMBINED WITH BROWNIAN DYNAMIC SIMULATION TECHNIQUES

An algorithm is developed in order to solve the stochastic Liouville e quation describing energy transfer between a donor-donor pair of reori enting chromophores. The algorithm requires the fluctuating part of th e Liouville equation in the form of trajectories. In this particular c ase the molecular reorientation of the chromophores was simulated by m eans of a Brownian dynamic simulation technique where each of the two molecules are allowed to undergo a restricted rotational diffusion in a cone potential. Numerical results are presented for the correlation function [chi(t)chi(0)], representing the probability that the initial ly excited donor still is excited at a later time t. Results are given for the weak or Forster regime and for a simple case in the strong or slow motion regime. The time resolved fluorescence anisotropy r (t) i s also calculated for different molecular reorientational rates and co ne potentials.