Computing Young's Modulus and Wall Thickness of Single-Walled Carbon Nanotubes with Atomistic Molecular Dynamics Simulations

All-atom molecular dynamics simulations are used to study in detail the behavior of several single-walled CNTs of different radii, lengths, and chirality under stretching and bending deformations, realized by imposing appropriate boundary conditions on the CNTs. The simulation results reveal unique scaling properties of the stretching and bending stiffness with respect to the CNT radius and length, which indicate that a single-walled CNT is best modeled as a thin cylindrical shell with a cross-sectional radius equal to the CNT radius and a constant wall thickness much smaller than the CNT radius and the separation of adjacent graphene planes in a graphite. The value of the surface Young's modulus is found to be roughly the same for all the single-walled CNTs simulated. By studying the thermal fluctuations of carbon atoms on the CNT wall, the wall thickness is determined to be about 0.45 Å for all the CNTs studied and correspondingly, Young's modulus is estimated to be about 8.78 TPa for these CNTs, irrespective of CNT radius and chirality.