Du Jiguang, Sun Xiyuan, Meng Daqiao, Zhang Pengcheng, Jiang Gang
Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan 610065, China.
J Chem Phys. 2009 Jul 28;131(4):044313. doi: 10.1063/1.3187525.
The geometrical and electronic structures of W(n) (n=2-16) clusters are investigated within the framework of a gradient-corrected density functional theory. The close-packed configurations are preferred for small tungsten clusters up to n=16. The most energetic favorable structures of W(14), W(15), and W(16) clusters, exhibiting similar electronic band structures, are all formed based on body centered cubic (bcc) unit. The clusters with size of n=8, 12, and 15 are found to be more stable with respect to their respective neighbors. The analyses of atomic orbit projected density of states and highest occupied molecular orbital, lowest unoccupied molecular orbital isosurfaces indicate that 5d electrons play a dominant role in the chemical activities of tungsten clusters. The clearly s-d hybridizations are primary presented in bonding W atoms of smaller clusters, as the cluster sizes increase, the 6p orbitals are gradually involved in chemical bonding. Our calculated vertical ionization potentials (VIPs) indicate that the W(8) and W(12) clusters correspond to the high VIPs. The vertical electron affinities are slightly underestimated in our investigation, but follow the trends of experimental data in principle.
在梯度校正密度泛函理论框架内研究了W(n)（n = 2 - 16）团簇的几何和电子结构。对于n ≤ 16的小钨团簇，密堆积构型更受青睐。W(14)、W(15)和W(16)团簇能量最有利的结构都基于体心立方（bcc）单元形成，且呈现出相似的电子能带结构。发现尺寸为n = 8、12和15的团簇相对于其各自相邻团簇更稳定。对原子轨道投影态密度以及最高占据分子轨道、最低未占据分子轨道等值面的分析表明，5d电子在钨团簇的化学活性中起主导作用。明显的s - d杂化主要出现在较小团簇的成键W原子中，随着团簇尺寸增加，6p轨道逐渐参与化学键合。我们计算的垂直电离势（VIPs）表明，W(8)和W(12)团簇对应于高VIPs。在我们的研究中，垂直电子亲和势略有低估，但原则上遵循实验数据的趋势。
