Adsorption of 5f-electron atoms (ThCm) on graphene surface: An all-electron ZORA-DFT study

All-electron calculations were performed to investigate the adsorption of 5f-electron atoms (An=ThCm) on graphene surface. The hollow site is energetically preferred for the An-graphene complexes studied. The interaction strengths between An and C decrease in the order of Th>Pa>U>Np>Pu>Cm>Am. The AnC interactions show predominately closed-shell characteristics, meanwhile ThC chemical bond formed through orbital overlaps of Th (6d) and C (2p) possesses partial covalent nature. The participation of 6d(5f)-electron into bonding orbitals are gradually weakened (enhanced) from Th to Pu because the 5f electrons are more and more diffuse. The physisorption nature of Am on graphene was observed by the weak orbital overlaps between Am (6d) and C(2p) and the half-fill 5f occupancy. The magnetic moments of An-graphene species are mainly derived from the 5f-electron due to its high delocalization. The molecular orbital (MO) and charge decomposition analysis (CDA) indicate that the 6d orbitals of An atoms play a more important role in participation of bonds relative to the 5f orbital, as well as the strong linear correlation between 6d occupancy numbers and adsorption energy highlights the significant role of 6d-electron of An in the interaction.