The pentagon-heptagon (5/7) pair in a zig-zag single-walled carbon nanotube was described as a dislocation by using the modified Peierls-Nabarro theory. The theory takes discrete effects, size effects and curvature effects into account. The bonds variation and shape distortion caused by 5/7 pair were evaluated. It was found that the neck bond (shared bond) became longer while the shoulder bonds became shorter comparing with the one of the hexagons. The results showed that the zig-zag chain across the center of the 5/7 pair will bend slightly in the axis direction towards the heptagon, and the tube will be flattened where the 5/7 pair was located because of the appearance of the internal stress and non-zero curvature.

A Dislocation Model for the Pentagon-Heptagon Pair in Zig-Zag Single-Walled Carbon Nanotubes. S.F.Wang, H.L.Zhang, X.Z.Wu: EPL, 2010, 90[5], 56004