Fig. 3.

Transition state and barriers for SW transformations. (a) Saddle point geometry computed for a counterclockwise bond rotation in a (10,0) tube (the bond is also tilted off plane). (b) Barriers for a number of tubes at different tension (ε = 0, 6%, and 12%) as a function of the angle β between the bond (in its initial position) and the tube axis. Small arrows indicate whether the exact computed barrier is above or below the analytical approximation of Eq. 3, plotted as a surface.