Figure 2: DFT calculations for the hybridization of the Alq3 LUMO with the Co surface.
From: Dynamic spin filtering at the Co/Alq3 interface mediated by weakly coupled second layer molecules
(a) Density of states projected over the Alq3 2p-N1, N2, N3 orbitals, which give the dominant contribution to three Alq3 LUMOs. The LUMO originating from the 2p-N1 orbitals is broadened into a band extending over the whole plotted energy range (black DOS). The other two LUMOs, which present a large contribution from the 2p orbitals of N2 and N3 (red and blue DOS), appear as two Lorentzian-like peaks centered at E−EF≈1.4 eV and E−EF≈0.3 eV, respectively. The energy splitting between these two peaks is largely affected by the distortion of the ligands, which determines a shift of the LUMO localized over N2 towards higher energies than that of the LUMO localized over N3. (b) DFT-optimized geometry for the Co/Alq3 interface. The two oxygen atoms and the nitrogen atom forming a strong covalent bond with the surface are labelled O1, O2 and N1. In contrast, the atoms labelled N2, N3 and O3 are much more separated from the surface. Colour code for the Co/Alq3 interface: Co (grey), Al (purple), C (yellow), O (red), N (dark blue) and H (cyan).
