Electronic structure of carbon nanotubes with an impurity point defect

A method for calculating the electronic structure of point defects in nanotubes is developed on the basis of the linear augmented cylindrical wave (LACW) method. The Green function of a defect nanotube is calculated using the Dyson matrix equation. The consideration is carried out in terms of the local density functional theory and the muffin-tin approximation for the electronic potential. Local densities of state are calculated for boron and nitrogen dopants in metal, semimetal, and semiconductor and chiral and nonchiral nanotubes. An increased density of states at the Fermi level is the most significant effect of boron and nitrogen dopants in metal nanotubes. In all semiconductor nanotubes, localized boron states close the optical band-gap. The effect of nitrogen atoms is restricted to a small rise in local densities of state at the Fermi level.