652438.fig.002a
(a)
652438.fig.002b
(b)
Figure 2: The primary gap Δ 𝐸 1 𝑔 (semiconducting single-walled carbon nanotubes) scales as 1 / 𝑟 (a), while for the curvature-induced band gap Δ 𝐸 2 𝑔 (small-gap semiconducting carbon nanotubes) scales as 1 / 𝑟 2 . At Δ 𝐸 1 𝑔 = Δ 𝐸 2 𝑔 = 0 relates to armchair nanotubes, which maintain their metallic character [4].