Quantum treatment of the optical spectra and the initial electron transfer process within the reaction center of Rhodopseudomonas viridis

The mechanism of the initial charge separation in the reaction centers of photosynthetic bacteria is examined together with optical spectra by quantum calculations within the INDO SCI approximation. A representative aggregate consisting of a bacteriochlorophyll dimer P, two bacteriochlorophyll monomers B_L and B_M as well as two bacteriopheophytines H_L and H_M and four histidine groups attached to the bacteriochlorophylls respectively is treated as a supermolecule. The coupling for the electron transfer between the initially prepared excited dimer state P* and the first detected charge separated state P⁺H_L^- is investigated and different mechanisms are discussed in view of these couplings.