First-principles study of optical spectra of single-wall B C2 N nanotubes

Abstract

First-principles calculations based on the density functional theory and the generalized gradient approximation were carried out to systematically investigate the optical properties of B C2 N nanotubes. Two types of zigzag nanotubes and two types of armchair nanotubes were considered. It was found that the optical properties of B C2 N nanotubes are closely related to their charility and diameter. Depending on the type of the nanotube, redshifts or blueshifts in the absorption peaks were observed which are due to the competition of the size effect and π orbital overlapping. Optical anisotropy with different light polarizations was also observed in the absorption spectra and loss function. The peaks in the loss function are attributed to the collective excitations of π electrons and the high-frequency π+σ plasmon. © 2006 The American Physical Society.