Molecular Dynamics Simulation of Intermediate Nanocrystal Regime of Au during the Process of Solidification
ZHANG Yan ning,WANG Li,BIAN Xiu fang (The Key Laboratory of Liquid Structure and Heredity of Materials,Ministry of Education,Shandong University,Jinan 250061,China) (Received 17 June 2002,accepted 29 August 2002)
We present a detailed molecular dynamics study of the microstructure,thermodynamics and kinetics of 1088 Au nanoclusters during solidification process within the framework of the embedded atom method. The results indicate that the two different solid structures are obtained under two different cooling rates.The system gets the crystalline state with the lower cooling rate,while becomes non crystal with the higher cooling rate. At the cooling rate of 1.5625×10 13 K/s,the energy temperature curve is approximately straight in the whole temperature regions,and the second peaks of the pair correlation function at the lower temperature splits into two sub peaks,showing the formation of the non crystal clusters.At the cooling rate of 1.5625×10 12 K/s,the energy temperature curve decreases abruptly at low temperature,and the crystalline peaks are obvious at the lower temperature,showing the formation of the crystal clusters. In addition,the changes of MSD with temperature have been investigated. It indicates that the rearrangement of atom positions is sensitive to the cooling rate in the process of solidification. During the higher cooling process,the atoms do not transfer in a wide range but only move within their neighborhood; while crystallization process is a diffusion process of atoms in a wide range and rearrangement process of atom positions.