Figure 4. Energy levels of the HOMO & HOMO-1 and LUMO & LUMO+1 orbitals as they computed

From

Synthesis, X­Ray Crystallography and DFT Studies of Ni(II) Complex with Tetradentate

Salem El-t. Ashoor, Hana B. Shawish

Physics and Materials Chemistry. 2015, 3(1), 7-11 doi:10.12691/pmc-3-1-2