Study of mechanical properties of nanoscale materials byab initio molecural dynamics and lattice green's function methods

Abstract

The atomistic and mechanical properties of the nanoscale materials are studied by using the ab initio molecular dynamics (TBMD) method and temperature dependent lattice Green's Function method. The calculated properties of carbon related nanoscale materials (e. g., carbon nanotube, nanographites and nanographenes) are compared with those of the corresponding bulk materials. We report that the thermodynamic and mechanical properties of the nanoscale materials are quite different from those of the corresponding bulk materials. For instance, it has been found that the excess energies of dislocations in the small crystallites are very small due to the atomistic "image effects". The edge dislocation in the carbon nanotubes, whose core is characterized by pentagon-heptagon pair is found to act as a center of the stress concentration and contribute to the peculiar nanoplasticity in the quasi one-dimensional (1D) cylindrical structures. The dislocation properties in nanographenes are studied by using the temperature dependent Lattice Green's Function Method.