Mechanical properties of MoS2 nanotubes under tension: a molecular dynamics study

We investigate the tensile properties of MoS2 nanotubes by the implementation of a set of molecular dynamics runs, using a recently developed version of the Stillinger–Weber (SW) potential. The nanotubes considered are of the H and T polytypes, with zigzag and armchair chirality. We found that only nanotubes of diameter greater or equal than 30 Å are stable when modelled by the SW potential. Zigzag nanotubes have a larger elastic modulus than armchair nanotubes of the same polytype and diameter, and T nanotubes deform more easily than H nanotubes. We also found that elastic modulus, tensile strength, and point of rupture depend on diameter when the diameters are less than 60 Å. We investigate the role of defects on the mechanical response, finding that, while elastic modules is not appreciably affected by the presence of vacancies, tensile strength, and point of rupture value decrease significantly, in particular when the defect is a vacancy of a whole MoS2 unit. The presence of a defect also affects the nature of the rupture, with the fracture becoming brittle. Increasing the temperature makes Young's modulus and tensile strength decrease. The mechanical response of chiral nanotubes is also investigated.