PLASMONS AND OPTICAL-PROPERTIES OF CARBON NANOTUBES

The optical properties of carbon nanotubes are studied within the gradient approximation. The calculated dielectric function exhibits many divergent structures, due to the divergencies in its density of states. As a result, the electron-energy-loss spectrum has many peak structures, including a prominent one at ∼6 eV, which is identified as the collective excitations of the π-band electrons. This plasmon is found to be insensitive to both radius and chiral angle, due to the unique one-dimensional band structure of carbon nanotubes. The result is consistent with the experimental measurements. The reflectance also exhibits many interesting features, including a weak but sharp plasmon edge at ∼6 eV. © 1994 The American Physical Society.