Fig. 4.

(A) LUMO and HOMO energy levels in PbRC (Left) and PSII (Right) in millielectron volts, calculated including the four (bacterio)chlorophylls and two (bacterio)pheophytins in the QM regions. Thick bars indicate [P_LP_M] and [P_D1P_D2]. (B) Correlation between calculated HOMO–LUMO gap and excitation energy in PbRC (Left) (coefficient of determination R² = 0.98) and PSII (Right) (R² = 0.98, excluding [P_D1P_D2]). [P_D1P_D2] does not fit to the correlation, because excitation of [P_D1P_D2] is excitation from HOMO of P_D1 to LUMO of P_D2 (A), which corresponds to charge transfer process, that is, the P_D1^•+P_D2^•– formation.