Calculations were made of the phase diagram of a two-dimensional planar crystal and of its wrapped version with defects under external homogeneous stress, as a function of temperature, using a simple elastic square lattice model that allowed for defect formation. The temperature dependence was found to be very weak. The results were applicable to stressing experiments on carbon nanotubes at high temperatures. With increasing stress, it was found that there was a cross-over regime which was identified with a cracking transition that was almost independent of temperature. An almost stress-independent melting point was also found. An enhanced ductility, with relative strains before cracking of between 200 and 400%, was also deduced; in agreement with carbon nanotube experiments. The specific values depended upon the Poisson ratio and the angle between the external force and the crystal axes. It was argued that the results for carbon nanotubes were not too different to the present results, in spite of the different lattice structures involved.

Modelling Two-Dimensional Crystals and Nanotubes with Defects under Stress. J.Dietel, H.Kleinert: Physical Review B, 2009, 79[24], 245415