Fig. 2.

Nucleation of a next atomic row on the growing tube edge (orange), at the catalyst (blue) surface, is shown as sketch-schematics (center) and in atomistic detail (A-F). (A-C) An armchair edge near the metal step on Ni (1, 1, 1), its side view (A), front view (B), and the emerging row segment flanked by the kinks (C). Similarly for a zigzag edge (D-F), its side view (D), front view (E), and the emerging nucleus: the row-segment with the end-kinks (F), which has higher energy than the armchair case in (C). The small left box in the schematics corresponds to the views (A) and (D) in the direction tangential to the tube wall, while the small right box corresponds to the views (C) and (F) in the direction normal to the surface.