Structure, energetics, and heteroatom doping of armchair carbon nanotori

Based on armchair carbon nanotubes (CNTs), we construct the structural models of symmetric armchair carbon nanotori of different tubular/radial diameters. Tight-binding (TB) calculations show that the energetic stabilities of these carbon nanotori rely on their symmetries and tubular diameters closely. Density functional theory (DFT) calculations on a carbon nanotorus with substitutional B/N doping reveal that B(N) dopant prefers to occupy heptagonal (pentagonal) sites in order to form a steady six π-electrons orbital. After B/N doping, the electron density of states (DOSs) near the Fermi energy are notablely enhanced. The pristine and doped carbon nanotori with diverse geometric and electronic properties provide new opportunities in the applications of nanotechnology.