Computational studies of carbon nanotube structures

Here we continue our previous exploratory work [Huhtala et al., Comput. Phys. Commun. 146 (2002) 30] in investigating carbon nanotube structures under different bending strain conditions by using large-scale molecular dynamics simulations. On the one hand bending strain is obtained by forcing nanotubes of different chirality to a closed toroidal configuration and on the other hand by bending a straight nanotube along a semicircle. Our previous work has indicated that the toroidal form buckles at a critical radius without changes in the local hexagonal bonding structure when the temperature is relatively low. Here this work has been continued by studying buckled tori at very high temperatures, where bond breakages in the form of pentagon-heptagon pair creation have been observed. These thermally excited defects seem to settle mainly in the unbuckled regions of the torus. The buckling phenomenon was also found to take place when straight single-walled nanotubes were bent along a semicircle. For a small and moderate amount of bending buckling behaviour seems similar to that observed in nanotori while for large bendings large structural deformations of the tube are observed. These include bond breakages and rupture, being dependent on the chirality of the tube. (C) 2002 Published by Elsevier Science B.V.