A group symmetry analysis of the Pauli master equation for the excitation energy transfer
in the cyclic arrangement of N (N=6-36) antenna Bchl molecules surrounding the bacterial
reaction center of Rhodopseudomonas viridis is performed. The group theory allows to find
analytic expressions for the most important observables (the antenna and reaction center
fluorescence intensities and the quantum yield of the transfer to the charge transfer
state) and to express their dependence on N. The time dependence of the fluorescence
intensities is given by two exponentials, however, a single-exponential approximation
can be used for t>to=4-25 ps. The quantum yield of the excitation energy transfer to the
reaction center charge transfer state is high (0.71-0.98) for the whole range of
physically acceptable values of the Forster radius Ro=46-96 A.