Effect of structural defects on the strength of adsorption of La and Lu species on graphene

By using DFT calculations, we addressed the influence of topological defects on the bonding strength and some electronic parameters for lanthanide atoms La-0 and Lu-0 ions La3+ and Lu3+ interacting with graphene. The results obtained for the cluster models containing isolated pentagon (5), Stone-Wales (SW) defect and pyracylene unit (5665), as well as for C-60 fullerene, were compared to those for a defect-free graphene model (G). We found that topological defects are always preferential sites for Ln" adsorption, as compared to pristine graphene. Particular orders of complex stability depend on lanthanide species, carbon cluster model, the Ln(n) position when the cluster has positive curvature (`endo', inside, or 'exo', outside), and are as follows: for La-0, 5665_endo > SW > 5_endo > 5_exo > 5665_exo > C-60 > G; for La3+, SW > G > 5665_endo > 5665_exo > 5_endo > 5_exo > C-60; for Lu-0, 5665_endo > 5_endo > 5_exo > SW > 5665_exo > C-60 > G; for Lu3+, SW > G > 5665 endo > 5endo > 5665 exo > 5_exo > Ln center dot center dot center dot C distances, frontier orbital energies, HOMO, LUMO and spin density plots, as well as charge and spin on Ln" species from Mulliken population analysis are presented.