Atomistic study of fracture of nanoscale materials by molecular dynamics and lattice Green's function methods

ne fracture behaviors of nanoscale sp-bonded materials have been studied us ing the molecular dynamics and lattice Green's function methods. Ile initia l atomic structures of the crack are determined both from the elastic solut ions as well as from those by lattice Green's function method for the infin ite systems. Firstly, we calculate the Green function for the defective lat tice, with dislocation and crack, by solving the Dyson equation, appropriat e for absolute zero temperature. After the lattice Green functions of the a bsolute zero temperature have been determined, the lattice parameters and i nteratomic force constants are adjusted to fit to materials at temperature T. In general, we have found that the lattice trapping and stress intensity factors for dislocation emission K-Ile. The fracture and strength properti es are also investigated for the nanocrystalline materials like semiconduct or quantum wire and nanotubes. The O(N) tight-binding molecular dynamics (T BMD) method is used to analyze the reconstruction of atomic bonding near th e crack tip as well as the cleaved surface. We compare the fracture behavio r of nanoscale materials with those of corresponding bulk-size materials.