Figure 1: A carbon nanotube ( 𝑛 , 𝑚 ) can be generated by rolling a graphene sheet along the chiral vector 𝐶 = 𝑛 𝑎 1 + 𝑚 𝑎 2 on the graphene sheet where 𝑎 1 and 𝑎 2 are graphene lattice vectors. The carbon nanotube can also be characterized by the diameter 𝑑 and the chiral angle 𝜃 with respect to the zig-zag axis, 𝜃 = 0°. The diagram represents a construction of a (8, 4) single-walled carbon nanotube [3].