Pdn(n=1~9)团簇的结构及磁性的第一性原理计算简

采用密度泛函理论中的广义梯度近似泛函BPW91和三参数杂化密度泛函B3LYP对Pdn(n=1~9)团簇的结构、稳定性和磁性进行了详细的计算.两种泛函得到了相同的稳定结构,除n=3、4外,两种方法得到的基态结构是完全一致的,但在n=3、4时用三参数杂化密度泛函B3LYP得到的基态结构与文献8,9,23]的相同.两种方法得到的平均配位数和平均键长有相似的变化规律,总体上随团簇尺寸的增大而增大,n=2~5时,增幅较大,n=5~9时,增幅较小.两种方法得到团簇能量的二阶差分、分裂能在n=4时均有较大的值,说明相对应的团簇具有较高的稳定性、较低的化学活性.两种方法得到团簇的平均每原子磁矩随团簇尺寸的增大有逐渐减小的趋势,个别团簇有振荡.结果表明两种泛函都可以描述团簇结构、稳定性和磁性的演变规律,但B3LYP泛函可以更加精确地描述Pdn团簇的结构演化.

Structures and magnetic properties of Pdn(n=1-9) clusters: First-principles calculation

Structures, stabilities, and magnetic properties of Pdn (n = 1-9) have been calculated by using the generalized gradient approximation functional BPW91 and three-parameter hybrid density functional B3LYP in density functional theory. The two functionals obtain the same stable structures, and get the same lowest-energy structures besides n=3,4, but the lowest-energy structures of Ni3 and Ni4 clusters by B3LYP functional are consistent with the configurations of references 8,9,23]. Average coordination number and average bond lengths by two functionals have similar patterns, in general increasing with cluster size increasing, which have a larger increase when n = 2-5 and have a smaller increases for n = 5-9. The second difference in energy and the first derivative of the total energy have a larger value for n = 4, which illustrate that the corresponding cluster have a high stability, low chemical activity by two functionals. Study of magnetic properties for Pd clusters indicates that the average magnetic moment of Pd atom has a gradually decrease trend. The results show that the two functionals can describe the evolution of structure, stabilities and of magnetism, but B3LYP functional more accurately describe the structure evolution of Pdn cluster.