Study Of The Structure Evolution And Ground State Energy Of Co-Cu Bimetallic Clusters By Using A Gupta Potential Combined With A Genetic Algorithm

Clusters, as aggregate of a few to several thousand atoms (even as much as a few millions), have many unique physical and chemical properties, and have attracted great concern. The geometries of clusters are fundamentals to understand the other physical and chemical properties and have great influence on the application and development of nano-materials. Structural properties of metal clusters can be very important for the performance of the micro-electronic devices and catalysts, and a great number of theoretical and experimental study of the structural and energetic properties of the pure clusters have been done in the last few decades. As the transition metal catalysts, cobalt and copper clusters are shown to be of great importance. But there is a few study about Co-Cu bimetallic clusters and no study can be found of ConCu55-n (n=0～55) bimetallic clusters with an icosahedron as the lowest energy structure of the pure Co55 (Cu55) cluster.In this work, the lowest energy geometrical structures of ConCu55-n(n=0～55) clusters were obtained by using a semi-empirical Gupta potential combined with a global optimization method. Our results are important for the future theoretical and experimental researches of larger systems. By calculation, our main results are as follows:1. The lowest-energy geometrical structures of bimetallic clusters were aberrance base on the icosahedral structure of the pure Co55 (Cu55) cluster.2. The distance of center of mass between Co and Cu like conk in the ground-state structure of Co55Cu55-n (n=0～55) bimetallic clusters. Separation of different kinds of atoms dominates in general.3. Started from the pure Cu55 cluster, the Co atom continuously replaces the Cu atom one by one, from the center to surface, and from the edge to vertex. The ground-state structure is related to the number of the Co-Co bond with the largest energy, Co-Cu bond with larger energy and the average bond length of those bonds.4. The icosahedral shell-like Co13Cu42 cluster has the most stable structure and 13 Co atoms occupy the whole inner part of the bimetallic cluster in which the two kinds of atoms separate absolutely.