Active sites electron energy levels

One way of calculating the electron energy levels of the various types of surface sites is to consider each type of site as a "surface complex" made up of the central, active atom surrounded by the neighboring "ligand" atoms. In an fee metal, a bulk metal atom is surrounded by twelve near neighbor ligands as shown in both top and side views from the 111 and 100 orientations in Fig. 4.3 This is the parent species and each of the possible surface complexes can be formed by the removal of the appropriate ligands from the parent. 

Figure 13. Left ligand field energy-level diagram calculated for plastocyanin. Center contains energies and wavefunctions of the copper site. Energy levels determined after removing the rhombic distortions to give and C symmetries are shown in the left and right columns, respectively (from Ref. 11). Right electronic structural representation of the plastocyanin active site derived from ligand field calculations (from Ref. 11).

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