Electronic properties of carbon nanotubes containing defects

The electronic structure of carbon nanotubes containing defects is investigated within a tight-binding framework. The electronic properties of the following defects are examined: (a) a hemispheric cap ending a (10, 10) tubule, (b) a pair of pentagon and heptagon aligned along the same side of the tube, which widens the diameter, (c) a pair of diametrically-opposed heptagon and pentagon, which bends de structure, and (d) sp(3)-like lines responsible for polygonization. In cases (a)-(c), a structural optimization was performed, either by minimization of a valence-force field adapted to the carbon network or by tight-binding molecular dynamics. (C) 1997 Elsevier Science Ltd.