自适应免疫优化算法研究大尺寸Cu-Au合金团簇稳定结构

合金团簇所具备的催化和光学等方面特性与团簇的尺寸、元素组成和元素序列密切关联,因而确定其稳定结构是研究纳米团簇合金性质的首要任务.本文利用基于内核构建的自适应免疫优化算法研究了完整元素组成的CunAum(n+m=61及79)二元合金团簇的稳定结构.应用多体Gupta势函数描述Cu-Au团簇原子间的相互作用.研究结果表明:对于CunAum(n+m=61)团簇,除了当n=12-15时为由三个双二十面体面面相连组成的环状结构外,其余均为二十面体结构.原子总数为79的Cu-Au合金团簇包括堆积缺陷的面心立方结构、双面心立方结构、二十面体、十面体和由四个双二十面体面面相连组成的环状结构.且当Au原子比例高和低时其主要构型分别为二十面体和十面体.此外,还分析了Cu-Au合金团簇结构势能量的分布情况及团簇的相对稳定性.原子分布规律显示Cu原子趋于占据内层,而Au原子趋向于分布在外层.

Stable structures of large scale Cu-Au clusters obtained by using adaptive immune optimization algorithm

Bimetallic clusters have been widely studied due to their special catalytic and optical properties, which is largely depended on the cluster sizes, compositions and atomic ordering. Therefore, much work has been done to locate their stable structures. In this paper, the stable structures of CunAum (n + m = 61 and 79) clusters are optimized by using an adaptive immune optimization algorithm based on the constructed inner cores. The many-body Gupta potential is applied to describe the interatomic interaction in Cu-Au clusters. Results showed that in CunAum (n + m = 61) clusters, the icosahedron is the dominant motif except for ring-like structures composed by three double-icosahedra at n = 12-15. The structures of 79-atom Cu-Au clusters can be categorized into stacking fault face centered cubic (fcc), twin fcc, icosahedron, decahedron, and ring-like structures composed by four double-icosahedra. Furthermore, the potential energies and the second finite energy differences of Cu-Au clusters are studied. Moreover, results showed that Cu atoms tend to be in the inner core, and Au atoms tend to occupy the outer shell sites.