A modified molecular structural mechanics method for analysis of carbon nanotubes

A modified molecular structural mechanics method, based on molecular mechanics and similar to the finite element method, was developed. The energy of a system was expressed by the force field functions of the molecular mechanics. Under the small deformation assumption and by the principle of minimum potential energy, the system function was established. The properties of tension and bending of single-walled carbon nanotubes were analyzed. The Young's modulus is about 0.36 TPa nm, which agrees perfectly with the results of previous analysis by other researchers. It is found, for the first time, that the Young's moduli, for Zigzag nanotubes, are different from each other when the system energy was expressed as the sum of two or three individual energy terms in molecular mechanics. Whereas, the Young's moduli were the same for the Armchair nanotubes. It is found, when simulating the bending, that the deflections are closer to the theoretical ones, of the classical elasticity, when the diameter of the carbon nanotube increases.