First-principles calculation of optical properties of C₆₀ in the fcc lattice

The electronic and optical properties of C₆₀ in the fcc lattice have been studied by a first-principles method. It is shown that C₆₀ has a low dielectric constant and an optical spectrum rich in structures; this is drastically different from diamond and graphite. The spectrum shows five disconnected absorption bands in the 1.4 to 7.0 eV region with sharp structures in each band that can be attributed to critical-point transitions. This is a manifestation of the localized molecular structure coupled with long-range crystalline order.