CCSD (T) study on the structures and chemical bonds of AnO molecules (An=Bk-Lr)

The molecular geometries and dissociation energies of AnO (An=Bk-Lr) molecules were first obtained at the CCSD (T) level of theory. Four hybrid functionals, B3LYP, M06-2X, TPSSh, and PBE0, were also employed in the calculations for the sake of comparison. Comparing with CCSD (T) results, B3LYP, TPSSh, and PBE0 functionals obtained more appropriate results relative to M06-2X and MP2. The analyses on molecular orbitals show that the 7s, 6d, and 5f atomic orbitals of actinide (An) atoms participate in the bonding of An-O bonds. The partial covalent nature between An and O atoms was revealed by QTAIM analyses.