Carbon nanotube chiral angle
= Carbon nanotube chiral angle
{title2=$\theta$}
The angle of the wrapping vector from the zigzag direction of <graphene>. For chiral indices $0\le m\le n$, $\theta=\tan^{-1}[\sqrt3m/(2n+m)]$, ranging from zero for zigzag tubes to 30 degrees for armchair tubes. Together with diameter, it determines the discrete wrapping geometry, but does not alone determine the observed colour of a nanotube suspension.