Optical absorption spectra and geometric effects in higher fullerenes

摘要

The optical excitations in $\rug$ and higher fullerenes, including isomers ofC$_{76}$, C$_{78}$, and C$_{84}$, are theoretically investigated. We use atight binding model with long-range Coulomb interactions, treated by theHartree-Fock and configuration-interaction methods. We find that the opticalexcitations in the energy region smaller than about 4 eV have most of theiramplitudes at the pentagons. The oscillator strengths of projected absorptionalmost accord with those of the total absorption. When the projection isperformed on each pentagon and pentagon dimers, the resultant spectrum in thelow energy region is quite different from that of the total absorption. Thespectral shapes of the total absorption are turned out to be determined mainlyby the geometrical distributions of the pentagons in the fullerene structures.