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 <i>C</i>_2<i>h</i> symmetry except for the C₆₀−10Au complex, for which <i>C</i>₂ symmetry was assumed. Two different configurations, namely η²⁽⁵⁾ and η²⁽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.