Structural relaxation in charged metal surfaces and cluster ions.
Structural relaxation in charged metal surfaces and cluster ions.
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DOI：
10.1002/smll.200600232
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发表时间：
2006-12
期刊：
影响因子：
13.3
通讯作者：
F. Weigend;F. Evers;J. Weissmüller
中科院分区：
文献类型：
--
作者：
F. Weigend;F. Evers;J. Weissmüller
空间电荷层可以显着影响金属电极表面的特性，例如通过改变表面介电响应或通过诱导原子弛豫间接影响。尽管人们努力利用这一概念来设计新型功能纳米材料，但人们对潜在的微观过程知之甚少。在这里，我们报告了由多达 309 个原子组成的 Au 簇离子中原子弛豫的密度泛函理论 (DFT) 研究。原子位移的适当平均值对充电的响应与宏观金单晶表面的实验观察一致。此外，总体 DFT 响应也与简单唯象模型的预测一致。受我们观察的启发，我们提出了一种情况，其中表面弛豫（“拉伸”）是由过量电荷施加在表面原子上的面外赫尔曼-费曼力引起的，并且面内表面应力本质上代表了表面层响应于拉伸的弹性横向收缩趋势。
Space-charge layers can noticeably affect the properties of metal electrode surfaces, for instance by modifying the surface dielectric response or indirectly via the induced atomic relaxations. While there are efforts to exploit this concept for designing novel functional nanomaterials, the underlying microscopic processes are poorly understood. Here, we report on a density functional theory (DFT) study of atomic relaxation in Au cluster ions comprising up to 309 atoms. Suitable averages over atomic displacements respond to charging consistent with experimental observation on macroscopic Au single-crystal surfaces. Moreover, the overall DFT response is also consistent with predictions of a simple phenomenological model. Motivated by our observations, we propose a scenario in which the surface relaxation ("stretch") results from out-of-plane Hellman-Feynman forces exerted on the surface atoms by the excess charge, and where the in-plane surface stress represents essentially an elastic transverse contraction tendency of the surface layer in response to stretch.