Reduced backscattering in potassium-doped nanotubes:: Ab initio and semiempirical simulations

By means of combined ab initio and semiempirical simulations, the charge transmission properties of potassium- and nitrogen-doped nanotubes are compared. The backscattering efficiency of adsorbed potassium is shown to be much weaker, owing to a shallower impurity potential well that weakly traps the induced quasibound states. The difference in conductance and elastic mean free paths is further investigated for nanotubes with lengths of several tens of micrometers and random distribution of dopants. Our results provide clear criteria for favoring doping by physisorption instead of chemical substitutions.