Carbon nanotube chiral vector
= Carbon nanotube chiral vector
{title2=$\mathbf C_h$}
The <graphene> translation $\mathbf C_h=n\mathbf a_1+m\mathbf a_2$ that becomes a tube circumference when its endpoints are identified. It determines wrapping indices and diameter $|\mathbf C_h|/\pi$; it is perpendicular to the tube axis.