COHERENCE, FRICTION, AND ELECTRIC-FIELD EFFECTS IN PRIMARY CHARGE SEPARATION OF BACTERIAL PHOTOSYNTHESIS

New electron transfer patterns have been revealed by the dynamics of t he special pair chforophyll, the auxiliary chlorophyll, and pheophytin in primary bacterial photosynthetic charge separation. We address her e several of these charge transfer features for which new elements of electron transfer theory, disregarded in common theoretical approaches to photosynthetic electron transfer, are needed. These features are, first, an auxiliary chlorophyll state weakly off-resonance relative to the special pair and pheophytin states. Common superexchange views fa il in this case, and incorporation of continuous vibrational manifolds in all three electronic states is essential. Secondly, external elect ric fields may induce transitions between the superexchange and sequen tial electron transfer modes where the vibrational manifolds ensure th at mild resonances rather than divergence appear in the rate constant at resonance. The sequential mode finally incorporates a variety of fr ictional patterns ranging from vibrationally almost relaxed transition s to strongly dynamically coupled, coherent transitions.