Density Functional Investigations of Endohedral Metallofullerenes TM@C24 (TM = Mn, Fe, Co, Ni, Cu, and Zn)

The theoretical investigations on TM@C-24 (TM = Mn, Fe, Co, Ni, Cu, and Zn) with different spin configurations have been performed by using the hybrid DFT-B3PW91 functional in conjunction with 6-31G(d) basis sets. The results show that the ground states of Fe@C-24 and Ni@C-24 are their spin triplet states, whereas the ground state of Co@C-24 is spin quartet state. Moreover, three Fe@C-24 isomers are favorable in energy. The HOMO and LUMO of Zn@C-24 indicates that there is no hybridization between Zn atomic orbitals and the C-24 cage orbitals. Natural population analysis shows that the charges always transfer from the TM atoms to the C-24 cage. In going from isolated TM atom to TM@C-24, the occupation of the 4s orbital is strongly reduced. (C) 2009 Wiley Periodicals, Inc. Int J Quantum Chem 111: 96-102, 2011