Structural and electronic properties of ultra-small radius SWCNT

Structural and electronic properties of an ultra-small radius single-walled carbon nanotube (SWCNT) were studied using density functional linear-augmented plane wave (LAPW) method. Different electronic properties of (4,0) SWCNT show this ultra-small radius nanotube could not be extracted from the simple folding of a graphene. The calculated value for diameter of the tube is 3.364 Å, in good agreement with experimental results. Density of states and band structure results show the metallic character of the (4,0) nanotube consistent with experimental results. A large van Hove peak near Fermi energy could be a good evidence for charge carriers to show superconductivity in a (4,0) nanotube. This calculation predicts that a (4,0) nanotube could be a stable structure as a freestanding SWCNT. It is also concluded that the density functional LAPW method gives reasonable electronic and structural properties of ultra-small radii SWCNTs, which are at least as good as the pseudopotential approach results.