x direction y direction z direction components in this direction present. As can be seen in Fig. , these atoms are in those parts of the molecules that show the largest density differences. Moreover, the positive y components of the electric fields are about double in magnitude for the Chl-c2 molecules than those for the Chl-c1 molecules. These field differences explain, that while the energy shifts for the two types of Chl-c molecules can be very similar in the case of the test fields above, the energy of the Chl-c2 molecule within the FCP protein is the lowest of all chlorophyll molecules.