Density-functional study of small neutral and cationic bismuth clusters Bin and Bi+n(n=2-24)
Density-functional theory with scalar-relativistic pseudopotential and a generalized gradient correction is used to calculate the neutral and cationic Bi,, clusters (2≤n≤24), with the aim to elucidate their structural evolution, relative stability, and magnetic property. The structures of neutral Bi clusters are found to be similar to that of other group-V elemental clusters, with the extensively studied sizes of n=4 and 8 having a tetrahedron and wedgelike structure, respectively. Generally, larger Bi clusters consist of a combination of several stable units of Bi4, Bi6, and Bi8. and they have a tendency to form an amorphous structure with the increase of cluster sizes. The curves of second order energy difference exhibit strong odd-even alternations for both neutral and cationic Bi clusters, indicating that even-atom (odd-atom) sizes are relatively stable in neutral clusters (cationic clusters). The calculated magnetic moments are 1μB for odd-atom clusters and zero for even-atom clusters. We propose that the difference in magnetism between experiment and theory can be greatly improved by considering the orbital contribution. The calculated fragmentation behavior agrees well with the experiment, and for each cationic cluster the dissociation into Bi4 or Bi+7 subclusters confirms the special stability of Bi4 and Bi+7. Moreover, the bond orders and the gaps between the highest occupied molecular orbital and the lowest unoccupied molecular orbital show that small Bi clusters would prefer semiconductor characters to metallicity.
H.K.Yuan H.Chen A.L.Kuang Y.Miao Z.H.Xiong
School of Physical Science and Technology, Southwest University, Chongqing 400715, Peoples Republic School of Physical Science and Technology, Southwest University, Chongqing 400715, Peoples Republic
国际会议
广州
英文
1402-1411
2008-11-01（万方平台首次上网日期，不代表论文的发表时间）