Computer simulation study of mechanical properties of nanoscale materials by molecular dynamics and lattice green's function methods

Abstract

The mechanical properties of nanoscale materials are studied using the molecular dynamics and lattice Green's function methods. The initial atomic structures of the dislocations and cracks are determined both from the elastic solutions as well as from those by lattice Green's function method for the infinite systems. Firstly, we calculate the Green function for the defective lattice, with dislocation and crack, by solving the Dyson equation, appropriate for absolute zero temperature. The thermal expansion and the temperature dependence of the interatomic force constants are determined by using the statistical moment method and they are taken into account in the lattice Green's functions. The strength and fracture properties are then investigated for the nanocrystalline materials like semiconductor quantum wire and carbon related materials like graphenes and nanotubes. The O(N) tight-binding molecular dynamics (TBMD) method is used to analyze the reconstruction of atomic bonding near the crack tip as well as the cleaved surface. We compare the mechanical properties of nanoscale materials with those of corresponding bulk-size materials.