Collective excitations in single-walled carbon nanotubes

In this Brief Report, we study the dispersion relations of plasma waves which propagate parallel to the surface of the single-walled metallic carbon nanotubes. We use the classical electrodynamics in our calculations. Electronic excitations on the nanotube surface are modeled by an infinitesimally thin layer of the pi and sigma electrons which is described by means of the two-fluid hydrodynamic theory.