Theoretical Study On The Structure And Phase Transition In Nanoclusters And The Mechanism Of Fracture Of Nanowire

Nanomaterials have been widely attended because of their novel physical and chemical properties, and the potential application. As a bridge between an isolated atom and bulk material, atomic cluster and nanowire attract increasingly interest.1. Basing on the classic molecular dynamic method, we proposed a kind of virtual prober method, using which, we have explored the growing process of Lennard-Jones clusters. The splitting and merging of the growth path are found. Results explained why some clusters containing atoms of specified numbers are prominent in mass spectrum.2. A definition of the surface atom of cluster is presented in the work, basing on which, we have found the compressing effect of the atomic shells on the internal structure of the cluster, more atomic shells will provide stronger compression on the cluster structure. Results reveal that compression from the outermost surface atomic shells is responsible for the dominance of icosahedra in small clusters.3. The study reveals that the surface melting of 147-atom Lennard-Jones (LJ147) cluster starts from the migrating and floating of the vertex atoms on the surface, which generally extends the understanding on surface melting of clusters. The collective vibration mode in LJ147 cluster was found and the attenuation of which was studied.4. Using classic molecular dynamics method, we have studied the fracture of <110> Au nanowire. Results reveal that lower temperature will prolong the fracture of Au nanowire, while stronger tensile stress will shorten the time needed by the nanowire to fracture. We found that a specified tensile stress will drive the nanowire transform from initial <110> orientation to <100> orientation.