铂金团簇结构与稳定性的密度泛函研究

采用随机踢球全局优化模型结合密度泛函理论系统,研究了Pt^λ_n(2≤n≤9,λ=0,-1)团簇的几何结构等微观性质,以及这些性质随着团簇尺寸变化的关系与演化规律.通过对计算结果理论的分析发现:中性与阴性团簇的基态构型在所研究的尺寸范围内更倾向于具有低对称性的三维立体结构;体系的平均结合能均随着铂金原子个数的增多而增大,阴性团簇平均结合能比相应的中性大;所有电荷态下团簇的离解能、二阶拆分能都随着铂金原子个数的增加呈现出明显的奇偶交替现象.结果表明:阴性的奇数团簇的稳定性要强于与之相邻的偶数团簇的稳定性;相反,中性团簇下偶数团簇的稳定性比奇数团簇强.

Density Functional Theory Study of the Structures and Relative Stabilities of Platinum Clusters

Based on the combination of saunders kick global minimum stochastic search and density functional theory, the structures, relative stabilities, as well as the relationship of these properties along with the cluster size have been systematically investigated for small bare platinum clusters Pt^λ_n(2≤n≤9, λ=0,-1). We found that, with the theoretical analysis of the calculating results: neutral and negative ground state configuration of the cluster in the size of the study in this article are more likely to have low symmetry within the framework of three-dimensional structure; the average binding energy of the system will increase with the increase in the number of platinum atoms, in addition, the average binding energy of negative clusters larger than the corresponding neutral; calculated dissociation energy and the second difference energy as a function of the cluster size exhibit a pronounced even-odd alternation phenomenon, indicating that odd-numbered clusters keep higher stability compared with their neighboring even-numbered clusters for charged platinum clusters, and the stability of even-numbered clusters is higher than that of the adjacent odd-numbered clusters for neutral platinum clusters.