To illustrate the correlation between bond overlap population diagram (BOPD) and EELS profile, Figure 4991a shows the measured CeF3 F-K ELNES.  The main structure width, including the large peak A and its shoulder B, was evaluated as the distance between the positions of the broken lines corresponding to the minimum and maximum in the second differentiated spectra.
Figure 4991a. The measured CeF3 F-K ELNES. Adapted from 
Figure 4991b shows the unoccupied partial density of states (PDOS) of CeF3 and the BOPD between Ce and its neighboring F for the non-core-holed, ground state electronic structures. The main peak structures of the ELNES in Figure 4991a correspond to the Ce5d derived states, which range from 5 to 9 eV above the Fermi level (the Fermi level in Figure 4991b is set to zero). Since the intensities of the BOPD are negative, the corresponding interactions between the Ce and anion F atoms are all antibonding. Larger BOPD intensities correspond to larger spatial overlaps between the two molecular orbitals, promoting higher antibonding energy levels.  The spatial overlaps between the Ce5d and the F orbitals show a variation in the Ce5d-derived states, resulting in the energy width of Ce5d PDOS and the main peak structures in the ELNES in Figure 4991a.
Figure 4991b. The unoccupied PDOS of CeF3 and the BOPD between Ce and its neighboring F for the non-core-holed, ground state electronic structures. Adapted from 
 Ikuo Nishida, Kazuyoshi Tatsumi and Shunsuke Muto, Local Electronic and Atomic Structure of Ce3+-Containing Fluoride/Oxide Determined by TEM-EELS and First-Principles Calculations, Materials Transactions, Vol. 50, No. 5 (2009) 952 - 958.
 D. G. Pettifor: Bonding and Structures of Molecules and Solids,
(Oxford University Press, 1995).