Quan Silong, Zhang Yuhua, Liu Haixin, Fan Yun, Zhou Qi, Feng Lin
Jiangxi Province Key Laboratory of Nuclear Physics and Technology, East China University of Technology, Nanchang, Jiangxi 330013, People's Republic of China.
School of Mechanical and Electronic Engineering, East China University of Technology, Nanchang, Jiangxi 330013, People's Republic of China.
Langmuir. 2024 Aug 13;40(32):16867-16874. doi: 10.1021/acs.langmuir.4c01408. Epub 2024 Jul 30.
Work function (WF) is one of the most fundamental physical parameters of metal surfaces, which can not only reflect the electronic structure of metal surfaces but is also very sensitive to the surface microstructure. In this paper, we use first-principles calculations to systematically study the strain effects on the vacuum level, Fermi level, and WF of the Au(111) surface. We find that the vacuum level and Fermi level of the Au(111) surface increase under compressive strain and decrease under tensile strain, and the effects of biaxial strain on the vacuum level and Fermi level can be equivalent to the superposition of two perpendicular uniaxial strains. These strain effects are attributed to the charge transfer induced by the strain. However, the change of WF with strain is the result of the competition between the strain effects of the vacuum level and Fermi level. That leads to the WF increasing with compressive uniaxial strain and decreasing with tensile uniaxial strain. Moreover, because the Fermi level is more responsive to compressive uniaxial strain, the Fermi level changes faster than the vacuum level under compressive biaxial strain. Consequently, the WF decreases with increasing tensile biaxial strain and slightly increases before decreasing with increasing compressive biaxial strain.
功函数（WF）是金属表面最基本的物理参数之一，它不仅能反映金属表面的电子结构，而且对表面微观结构也非常敏感。在本文中，我们使用第一性原理计算系统地研究了应变对Au(111)表面真空能级、费米能级和功函数的影响。我们发现，Au(111)表面的真空能级和费米能级在压缩应变下升高，在拉伸应变下降低，双轴应变对真空能级和费米能级的影响等同于两个垂直单轴应变的叠加。这些应变效应归因于应变引起的电荷转移。然而，功函数随应变的变化是真空能级和费米能级应变效应之间竞争的结果。这导致功函数在单轴压缩应变下升高，在单轴拉伸应变下降低。此外，由于费米能级对单轴压缩应变更敏感，在双轴压缩应变下费米能级的变化比真空能级快。因此，功函数随双轴拉伸应变的增加而降低，在随双轴压缩应变增加而降低之前略有升高。
