ELECTRONIC-STRUCTURE OR SC-AT-C-60 - AN AB-INITIO THEORETICAL-STUDY

We have studied the electronic structure of Sc@C-60 at the self-consistent-field Hartree-Fock (SCF-HF) level of theory employing a double-zeta (DZ) basis set. Binding energies have also been calculated employing a hybrid of HF and density functional theory (herein denoted as-HF-BLYP), Several electronic states in C-5v and C-3v symmetry were considered. A double-minimum configuration is found for the open-shell (4)A(2) electronic ground state in C-5v symmetry. The lowest energy minimum has Sc located 1.175 Angstrom away from the center of the cage, approaching a C-60 pentagon along a C-5 axis. Bonding between the Sc-atom and the case occurs by donation of the 4s electrons to the lowest unoccupied orbital of C-60 and by 3d electron interaction with the antibonding orbital associated with the five double bonds radiating from the pentagon closest to Sc (similar to 2.5 Angstrom). The other local minimum has Sc located at the center of the cage and is predicted-to be 1.2 eV higher in energy at the highest level of theory employed in this work (DZ/HF-BLYP). The energy barrier for moving Sc from the center of the cage to the lowest energy position is predicted to be 0.1 eV at the same level of theory.