Ab initio study of dititanium endofullerenes:: D5d- and D5h-Ti2@C80

Theoretical ab initio studies of the structure and electronic properties of two dititanium endofullerene isomers Ti-2@C-80 with D-5d and D-5h symmetry were carried out. For each configuration, optimized atomic structures were obtained using RHF-level (STO-3G* basis) calculations. The electronic structure and atomic charges of endoftillerenes were computed by the DFT method in the discrete variation approach. The results were analyzed in comparison with "empty" D-5d-, D-5h-C-80 fullerenes. The obtained charge density maps show that the valence states of Ti atoms in D-5h-Ti-2@C-80 overlap with those of the C-80 cage indicating the existence of covalent bonding between titanium and the carbon cage. The atomic charge of each Ti atom inside the C-80 cage is equal to +1.9 e providing a formal ionic state of the dititanium endofullerene (Ti2+)(2)@C-80(4+). (c) 2005 Elsevier B.V. All rights reserved.