Ni_n(n≤8)团簇的密度泛函研究(英文)  

Density functional theory study of small Ni_n(n≤8)clusters

作　　者：阎世英[1] 江海[1] 杨自钦[1] 朱正和[2] 

机构地区：[1]青岛大学物理科学学院,青岛266071 [2]四川大学原子与分子物理研究所,成都610065

出　　处：《原子与分子物理学报》2012年第2期281-290,共10页Journal of Atomic and Molecular Physics

基　　金：Project supported by Higher School Science and Technology Projects of Shandong Province,China(J10LA02)

摘　　要：用高斯程序的B3LYP交换相关函数和全电子基组DGDZVP、TZVP优化了Ni_n、Ni_n^+和Ni_n^-(n=2～8),得到了这些体系的基态几何构型、离化能、电子亲和能以及键能.结果表明:Ni_2,Ni_3,Ni_4,Ni_5和Ni_6团簇的基态分别是5,7,9,11和13重态.表明:Ni_2,Ni_3,Ni_4,Ni_5和Ni_6团簇中分别有4,6,8,10和12个平行自旋的电子,在每一个Ni_n团簇中非耦合的电子是最多,这些电子占据不同的轨道,导致每一个Ni_n团簇的能量最小,说明在这些Ni_n团簇中电子平行的效应大于电子耦合的效应,这显然与d电子的离域效应有关,这被称为自旋极化效应,符合宏特规则.Ni_n、Ni_n^+和Ni_n^-(n=2～8)体系的磁矩分别是Ni_n具有8μB(n=6～8),Ni_n^+具有9μB(n=6～8),Ni_n^-具有7μB(n=4～8).Density functional theory BSLYP has been performed on the calculations of structure of Ni,, Ni＋ and Nin（n≤8）. For both neutral and charged systems, many lowlying states and different mul tiplicities are studied in order to find the lowest energy structures. DGDZVP allelectron basis sets and TZVP allelectron basis sets are employed. Equilibrium geometries, ionization potentials, electron affin ities and binding energies are reported. Our results show that the ground state for the Ni2 cluster is 5 multiple state, Ni3 cluster is 7multiple state, Ni4 cluster is 9multiple state, Nis cluster is 11multiple state, Ni6 cluster is 13multiple state, which indicate a spin polarization effeet in the Nin（n≤8） clusters. That is, there are 4 parallel spin electrons in Ni2cluster, 6 parallel spin electrons in Ni3cluster, 8 parallel spin electrons in Ni4 cluster, 10 parallel spin electrons in Nis cluster, 12 parallel spin electrons in Ni6 clus ter. The number of nonconjugated electrons in each ground state cluster is the greatest. These electrons occupy different spacious orbitals so that the energy for each Nin（n≤8） cluster is minimized. It can be concluded that the effects of parallel spin in the Nin（n≤8） clusters is larger than the effects of the conju gated clusters, which is obviously related to the effect of electron d delocalization. This condition is spin polarization effect of the Nin（n≤8） clusters. Our study has great significance for GMR （Giant Magneto Resistive）. Moreover, by studying the magnetic moments of Nin Ni＋ and Nin（n≤8） clusters, we find that the spin magnetic moments of Nin（n≤8） are 8ub the spin magnetic moments of Ni.＋ （n=68） are B and the spin moments of Nin（n≤8） are all . This study is helpful for understand ing giant magnetoresistive effect of transition metal clusters. Finally the results show that the stable structures of Ni clusters are sometimes different from that of Ni. clusters.

关 键 词：Nin 团簇 基态 自旋极化 

分 类 号：O642[理学—物理化学]