At this point, we seek to understand the effect of the electrostatic environment (protein, lipids, solvent, and ions) on the electronic structures of the chlorophyll molecules. To this end, we have calculated the density difference between the ground and the Q y excited state of the Chl-c molecules as shown in Fig. when comparing the results with and without QM/MM coupling in Fig. . Nevertheless, for LH complexes containing only Chl-a pigments, these small changes are important for forming the energy ladder in those systems. Moreover, the finding of the large difference densities for the Chl-c1 and Chl-c2 pigments corroborates the unexpected energy shifts for these pigments within the FCP complex of the diatom P. tricornutum.