Energy optimum chiralities of multiwalled carbon nanotubes

The energy optimum chiralities of neighboring layers of a multiwalled carbon nanotube (MWNT) are found to correlate with each other. Nearly identical chiralities are energy optimum in MWNTs with a large diameter. For a small tube, the chiral angle ratio of the outer to inner tubes decreases monotonically with decreasing tube diameter, and nearly identical zigzag chiralities become dominated for a very small tube. It is expected that low temperature control is necessary for achieving the optimum chiralities. The theory can explain most existing chirality characterizations of MWNTs synthesized at low temperature.