Carbon nanotubes: I. Geometrical considerations Original Research Article

The geometrical conditions pertaining to closure, helicity, and interlayer distance between successive layers with circular cross-sections in carbon tubules (nanotubes) have been examined. Both the intralayer length of the CC bonds and the interlayer distance between successive layers must vary with the radius of the layers. The division into groups of the sheets in nanotubes is found to be due to the reciprocal interaction of the interlayer distance variations and of the conditions required to maintain constancy of the pitch angle.