Chemistry Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085, India.
J Phys Condens Matter. 2010 Nov 3;22(43):435001. doi: 10.1088/0953-8984/22/43/435001. Epub 2010 Oct 7.
Using state-of-the-art first-principles calculations we report the interaction of M atoms (M = Cu, Ag and Au) with small Ag(n), Au(n) clusters (n = 3 and 6) and periodic Ag(111) and Au(111) surfaces. All calculations were performed using the plane wave pseudo-potential approach under the spin polarized version of the generalized gradient approximation scheme. The result shows that the equilibrium geometry of all MAg(3) and MAu(3) clusters favor a planar rhombus structure. From the charge distribution analysis of MAg(n)/MAu(n) clusters it is found that, while Cu and Ag donates electronic charge towards the host clusters, the Au atom acts as an acceptor, thus creating charge polarization in the system. The difference in orbital decomposed charges before and after the M interaction reveals that enhanced s-d hybridization is responsible for keeping the MAu(6) cluster planar, and increased p-orbital participation induces three-dimensional configurations in MAg(6) clusters. The optimization of M atom deposition on the Ag(111) and Au(111) surfaces shows that M atoms prefer to adsorb on the threefold fcc site over other well-defined sites. From the orbital decomposed charge analysis it is inferred that, although there is significant difference in the absolute magnitude of the interaction energy between M atoms and the Ag or Au substrates, the nature of chemical bonding is similar for the finite size clusters as well as in slab models.
利用最先进的第一性原理计算,我们报告了 M 原子(M = Cu、Ag 和 Au)与小 Ag(n)、Au(n)团簇(n = 3 和 6)以及周期性 Ag(111)和 Au(111)表面的相互作用。所有计算均在自旋极化广义梯度近似方案下使用平面波赝势方法进行。结果表明,所有 MAg(3)和 MAu(3)团簇的平衡几何形状都有利于平面菱形结构。从 MAg(n)/MAu(n)团簇的电荷分布分析可以看出,虽然 Cu 和 Ag 向宿主团簇提供电子电荷,但 Au 原子作为受体,从而在系统中产生电荷极化。M 相互作用前后轨道分解电荷的差异表明,增强的 s-d 杂化负责保持 MAu(6)团簇的平面构型,而增加的 p 轨道参与诱导 MAg(6)团簇的三维构型。M 原子在 Ag(111)和 Au(111)表面上的沉积优化表明,M 原子优先在三重 fcc 位上吸附,而不是在其他明确定义的位上。从轨道分解电荷分析可以推断,尽管 M 原子与 Ag 或 Au 衬底之间的相互作用能的绝对值存在显著差异,但对于有限尺寸团簇以及在薄片模型中,化学成键的性质是相似的。