The results from different levels of theory shown in Fig. and listed in Table agree in the fact that the Chl-c2 pigment has the lowest Q y excitation energy. Moreover, the pigment Chl-c1 has the second-lowest energy, except for the DFT/MRCI calculation on the QM/MM optimized geometry. This finding is unexpected, since the Q y excitation energies of Chl-c molecules in vacuum and in the organic solvents acetone and ether are blue-shifted with respect to those of Chl-a molecules . To decipher this energy ordering in FCP and to get insight into the associated discrepancy in organic solvents and vacuum, we optimized the geometries of the Chl-a and Chl-c1/c2 pigments in gas phase using the B3LYP level of theory together with the Def2-TZVP basis set. Subsequently, TD-LC-DFTB, TD-LC-DFT (CAM-B3LYP/Def2-TZVP) and DFT/MRCI calculations were performed. Furthermore, we have performed simulations of individual Chl-a and Chl-c1/c2 molecules in the solvents diethyl ether and acetone. 1 ns-long QM/MM MD simulations were followed by TD-LC-DFTB calculations within the QM/MM scheme to obtain excited state energy distributions.