Effective Screening of Localized Charged Perturbations in Metallic   Nanotubes: Roles of Massive Bands
  The massive-band effects on screening behavior of metallic carbon nanotubes are theoretically investigated using two different methods; continuous and lattice quantum theories. Both approaches show screening of a localized external perturbation with an effective screening length of the order of the nanotube diameter. Calculating the nonlinear deformation of the local density of states near the charged perturbation, we show that the perturbative effects of the massive bands are effectively canceled by direct massive band interactions, such that a good agreement between the two methods can be achieved. The effective screening is important in nanoscale integration of nanotube-based electronic devices. 
K. Sasaki, A. A. Farajian, H. Mizuseki and Y. Kawazoe