Atomistic elucidation of mechanical properties and fracture phenomenon of defective indium selenide monolayer

This study reports the mechanical properties and fracture mechanism of pre-cracked and defected InSe nanosheets using molecular dynamics (MD) simulations. We observed a brittle-type failure of the defective InSe nanosheets. Armchair directional bonds exhibit a higher resistance of crack propagation relative to the zigzag directional ones. Thus, the fracture strength of the pre-cracked sheet is slightly higher for zigzag directional loading than that for the armchair loading. We evaluated the limitation of the applicability of Griffith's criterion and Quantized fracture mechanics (QFM) theory for a single layer (SL) InSe sheet with nano-cracks. The brittle failure of Griffith's prediction demonstrates significant differences with the MD-predicted fracture strength. We investigated the effect of temperature on the mechanical properties of the pre-cracked samples of SLInSe. Furthermore, the impact of crack tip vacancy interaction is discussed. It has been demonstrated that inducing a certain amount of vacancies around the specific areas of a pre-cracked sample can enhance the strength of the material. We also discussed the fracture mechanism of both defected and pre-cracked structures at length.