It has been recognized that it is necessary to construct a microscopic model, with which one can reconstruct all the experimentally observed characteristics including temperature effects of the photosynthetic reaction centers (RCs). In such a model, we propose a set of parameters including energy levels of electronic states, vibrational mode frequencies, the coupling constants and the inhomogeneities. The values of these parameters are obtained by analyzing the absorption spectra of Rb. sphaeriodes RCs (R26 and K26.Phe-n mutants). Moreover, A thermal expansion model is introduced to treat temperature dependent peak shifts observed in the absorption spectra of the RCs. With this full microscopic description, we calculate the electronic coupling constants and rate constants between the involved states of some dynamic steps in RCs, i.e. electron transfer, energy transfer and internal conversion. For the electron transfer processes, we also study their temperature dependence.