Ab initio density functional theory calculations of the interactions between isolated infinitely-long semiconducting zig-zag (10,0) or isolated infinitely-long metallic arm-chair (5,5) single-walled carbon-nanotubes and single oxygen-molecules were carried out in order to determine the character of molecular-oxygen adsorption and its effect upon the electronic transport properties of single-walled carbon nanotubes. A Green’s function method, combined with a nearest-neighbor tight-binding Hamiltonian in a non-orthogonal basis, was used to compute the electrical conductance of single-walled carbon nanotubes and its dependence upon the presence of topological defects in single-walled carbon nanotubes and of molecular-oxygen adsorbates. The results showed that, in both semiconducting and metallic single-walled carbon nanotubes, oxygen-molecules were physisorbed at the defect-free nanotube walls but, when such walls contained topological defects, oxygen-molecules became strongly chemisorbed. In semiconducting (10,0) single-walled carbon nanotubes, physisorbed O2-molecules were found to increase the electrical conductance significantly while the effect of 7-5-5-7 defects was essentially annulled by chemisorbed O2-molecules. In metallic (5,5) single-walled carbon nanotubes, both O2 adsorbates and 7-5-5-7 defects were found to have a relatively small effect upon the electrical conductance.

The Effect of Topological Defects and Oxygen Adsorption on the Electronic Transport Properties of Single-Walled Carbon-Nanotubes. M.Grujicic, G.Cao, R.Singh: Applied Surface Science, 2003, 211[1-4], 166-83