Theoretical Investigation of Electronic Structures and Properties of C₆₀−Gold Nanocontacts

A theoretical study was performed to understand the structures and properties of C60-gold nanocontacts. In this investigation, C60 was sandwiched between gold clusters. In the studied clusters, the number of Au atoms varied from 2 to 8 on each side of C60. Molecular geometries of the investigated complexes were optimized at the density functional theory level, employing the B3LYP functional. The 6-31G(d) basis set was used for carbon atoms, while the LANL2DZ effective core potential was used for gold atoms. Geometries of all complexes were optimized under C2h symmetry except for the C60-10Au complex, for which C2 symmetry was assumed. Two different configurations, namely eta(2(5)) and eta(2(6)), for the binding of Au clusters with C60 were considered. It was revealed that complexes corresponding to the latter configuration are more stable than those having the former one. Ground-state geometries of the complexes involving odd numbers of gold atoms on each side of C60 were found to be represented by the triplet configuration. The HOMO-LUMO energy gaps of C60-gold complexes were found to be lower than that of isolated C60. The charge transport properties in the studied system are discussed in terms of molecular orbitals and the Fermi level.