Co-Ag与Co-Au合金团簇核层结构模拟

钴基二元合金团簇具有特殊催化和电磁性能已成为研究的热点.探究Co-Ag与Co-Au团簇稳定结构是研究其性质的重要步骤.运用基于内核构建的自适应免疫优化算法对大尺寸Co_(55)Ag_n、Co_(55)Au_n(n=1-55, 60, 70, 80, 92)团簇结构进行优化.基于紧束缚势二阶矩近似的多体Gupta势函数被用于描述合金团簇原子间相互作用.计算结果显示Co_(55)Ag_n、Co_(55)Au_n(n=1-55, 60)最稳定结构的主要构型为Mackay二十面体.原子分布分析显示Co原子位于内层,而Ag、Au原子均趋于分布在外层,呈现出核层状态.对于大尺寸Co_(55)Ag_n、Co_(55)Au_n(n=80, 92)团簇,Co-Ag团簇采取无定形结构,而Co-Au团簇为规则的二十面体结构.

Modelling of core-shell structures of alloy Co-Ag and Co-Au clusters

The special catalytic and electromagnetic properties of cobalt-based binary alloy clusters have become a hot research topic. In order to explore their properties, it is necessary to determine the most stable structures. The structures of large-scale Co55Agn and Co55Aun (n = 1-55, 60, 70, 80, and 92) clusters were optimized by an adaptive immune optimization algorithm based on the constructed inner cores. The many-body Gupta potential function based on the tight-binding potential second-order moment approximation was used to describe the interatomic interaction in Co-Ag and Co-Au clusters. Results showed that the most stable structures of Co55Agn and Co55Aun (n = 1-55, 60) are mainly based on the Mackay icosahedra. The analysis of atomic distribution showed that the Co atoms are located in the inner layer, while the Ag and Au atoms are located in the outer layer, appearing core/shell configuraitons. For Co55Agn and Co55Aun (n = 70, 80, and 92) clusters, Co-Ag clusters adopt amorphous structures, but Co-Au clusters have Mackay icosahedral motifs.