Structure And Energy Of Copper Clusters Studied By Computer Simulation

The study of clusters has become an increasingly interesting topic of research due to their particular geometric structures, unique physical and chemical properties and potential applications. Copper cluster being metallic clusters are particularly interesting for their potential use in many processes like catalysis; nanotechnology and new electronic materials.In this dissertation, methods and process of copper cluster studies were introduced, and optimization of atomic global optimization methods employed in structural molecular clusters, semi-empirical potentials and empirical potentials were reviewed. In this study, an embedded-atom method (EAM) was utilized to investigate the energy and structure of copper cluster by Monte Carlo computer-simulation. The main workscontained in the dissertation include:1. Methods and process of copper cluster studies were introduced, and optimization of atomic global optimization methods employed in structural molecular clusters, semi-empirical potentials and empirical potentials were reviewed.2. Embedded-atom method was utilized to investigate the energy and structure of Cu_n(n=13, 55) by Genetic algorithm, and the results were contrast with results gained by Monte Carlo method. Monte Carlo method was employed in global optimization of copper cluster.3. The structure and binding energy of copper clusters size range 2 to200 were studied by using embedded-atom method and Monte Carlo method. Stability of clusters structure was studied by calculation of binding energy for per atom, first difference energy and second difference energy of copper cluster. Most of copper cluster in size n=2-200 adopt structure based on icosahedral structure. We found that fcc-like and decahedral-like structure at n=6, 13, 19, 23, 26, 39, 49, 55, 68, 77, 90, 95, 117, 121, 131, 142, 153, 173, 189.The results show that the cluster growth is predominantly icosahedral, with island of fcc and decahedral growth. Most stable structure for copper clusters are found at n=6,13,19, 23, 26, 39, 49, 55, 68, 77, 90, 95,117,121,131,142,153,173 and 189.4. Cu_n (n=55) +Ar system were simulated by use of Monte Carlo method and Embedded-atom method. The results are same with results gain by simulation without Ar atom. These shows that buffer atom dos not affect copper cluster growth.5. Embedded-atom method was utilized to investigate the energy and structure of Cu561and Cu2500 by Monte Carlo computer-simulation. Although we do not reach final result of Cu2500, we can find the growth of Cu2500 is predominantly icosahedral. This result shows that the critical size for copper cluster is not at n=2500.