Investigation of Freezing Temperature Effect on Structural Transformation for Cu-58 and Cu-59 Clusters by Atomic Simulations

摘要

By means of molecular dynamics (MD) simulations at atomic scale, atom movements and packed structures are observed by condensing two liquid copper clusters respectively containing 58 and 59 atoms within the framework of the embedded-atom method (EAM). In this work we offer structural characterizations of the above simulated systems, and local structure changes are demonstrated by pair analysis according to their local environments. Concerning lowering the quenching temperature, the simulation results for the two clusters reveal how the atom movements can cause strong differences in structural changes by identifying internal energy, and pair analysis as well as atomic packing. In high quenching temperature regimes, the atoms in both of the two clusters move continuously, and they are packed disorderly. As the freezing temperature is decreased, the atom movements present different behaviors. For the Cu-58 cluster, the ordered packing fraction is apparently lower than that for the Cu-59 cluster, and the atom packing cannot present the ordered configuration. For the Cu-59 cluster, the whole cluster can present the icosahedral (lh) configuration at 300 K, though some atoms interchange their positions in this cluster. The simulations show sensitivities of the structural changes to the two small size clusters with adding or removing one atom.