混合团簇Cu_(13-n)Ag_n(n≤13)基态结构的遗传算法研究

Structures of ground-states of cluster Cu_(13-n)Ag_n(n≤13) studied by genetic algorithm

在混合团簇基态结构优化的遗传算法方案中增加了交换算子,结合Gupta紧束缚模型势研究了Cu13-nAgn团簇的最低能量结构,选择合适的交换和杂交概率,可有效地提高优化效率,优化结果表明,Cu13和Ag13是全对称的二十面体,n=1～10的混合团簇能形成稳定结构,其构型是在二十面体基础上发生畸变,Cu原子趋于处在团簇中心,随着Ag原子数目的增加,原子间的平均距离单调增加,团簇的结合能单调减小,Cu2Ag11和CuAg12只存在亚稳结构。

The structures and stabilities of the ground-states for Cu_(13-n)Ag_n clusters have been studied by Gupta model potential based on tight binding second moment approximation in combination with a genetic algorithm. It is found that the lowest energy structures of the pure clusters (n=0,13) are perfect icosahedron, and the structures for the bimetallic clusters (n=1～10) have stable structure which are slightly deformed with respect to the perfect icosahedron, The Cu atom prefers to occupy the center of the clusters with higher coordination numbers. With increasing the number of Ag atoms, the average distance between the closest atoms in the Cu_(13-n)Ag_n clusters increased monotonously, and the average binding energy of the ground-states decreased monotonously.