Figure 1
From: Self-assembly of a parallelogram black phosphorus ribbon into a nanotube
Geometry of a rectangular BP ribbon and possible nanotube from the ribbon with three principle directions, i.e., e 1, e 2 and e 3. (a) Top view of SLBP; (b) zigzag-view of SLBP; (c) armchair-view of SLBP; (d) unit cell with bond lengths of L 12 = L 13 = L 45 = L 46 = 0.24244 nm, L 14 = 0.23827 nm, and bond angles of α = 98.213°, β = 97.64°; (e) Armchair BPNT (A-BPNT), which is formed by curling the armchair sides of SLBP within the red rectangular in (a); (f) Zigzag BPNT(Z-BPNT), obtained by curling the zigzag sides of SLBP within the blue rectangle in (a). For simplicity, using (N A, N Z) labels the chirality of a BPNT, where N A and N Z are the numbers of periodic cells along the armchair and zigzag directions within the cross section, respectively, e.g., N A = 12, N Z = 0 in (e). For a chiral BPNT, both N A and N Z are different from zero.
