  In this paper, we investigate the non-Markovian dynamics of a model to mimic
the excitation energy transfer (EET) between chromophores in photosynthesis
systems. The numerical path integral method is used. This method includes the
non-Markovian effects of the environmental affects and it does not need the
perturbation approximation in solving the dynamics of systems of interest. It
implies that the coherence helps the EET between chromophores through lasting
the transfer time rather than enhances the transfer rate of the EET. In
particular, the non-Markovian environment greatly increase the efficiency of
the EET in the photosynthesis systems.
