Fe—Ni混合团簇基态结构的遗传算法研究

Study of the ground-state geometric structures of bimetallic clusters Fe-Ni with a genetic algorithm

采用半经验的Gupta多体势结合遗传算法对不同组分的Fe_nNi_m(N=n+m,N=13,38)混合团簇的基态结构和性质进行了模拟研究.结果显示:总原子数为13的混合团簇基态几何构型是基于单质团簇的基态二十面体结构,并且随着Fe原子数的增加表现出Fe原子首先占据中心位置的规律性;对总原子数为38的混合团簇,在轻混合(类掺杂)情形(n≤15,34≤n≤38)下基态几何构型为类似于纯单质团簇基态的截角八面体结构,而在重混合(n=16～33)时基态几何结构表现为不同于单质团簇的类截角二十面体构型;分析二级差分能表明Fe_1Ni_(12)、Fe_7Ni_(31)及Fe_(14)Ni_(24)具有相对高的稳定性,我们提出了基于有效键数的简化模型以解释此幻数结构序列.

We use Gupta many-body potential combined with genetic algorithm to perform a systematic study of the ground state structural properties of the bimetallic clusters FenNim （n＋m=13, 38）. Our results show that the ground-state geometric structures of the 13-atom bimetallic clusters all possess the icosahedron, and the Fe atoms tend to occupy the central part of the icosahedron priorly with incressing the number of Fe atoms; The truncated octahedra are identified as the ground-state geometries of the 38-atom bimetallic clusters FenNim in the range of n≤15 and 34≤n≤38, otherwise an icosahedral fragment prefers. Fe1Ni12, Fe7Ni31 and Fe14Ni24 are recognized as the magic-number clusters, and we proposal a simple model based on the effective number of bonds to explain the reason