  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.
