Molecular dynamics study of the fracture of single layer buckled silicon monosulfide and germanium selenide

Molecular dynamics simulations were conducted with the Stillinger–Weber potential at room temperature to study the mechanical properties and find the mode-I critical stress intensity factor of buckled two-dimensional (2D) hexagonal silicon mono-sulfide (SiS) and germanium selenide (GeSe) sheets. Uniaxial tensile tests were simulated for pristine and pre-cracked sheets. 2D Young’s modulus of SiS and GeSe are estimated at 38.3 and 26.0 N/m, respectively. Their 2D fracture strength is about 3.1–3.5 N/m. By using the initial crack length with the corresponding fracture stress, their mode-I critical stress intensity factor is estimated in the range from 0.19 through 0.22 MPapm. These values differ within 5% from those obtained by the surface energy and are very small compared to the reported fracture toughness of single-crystalline monolayer graphene.