Atomic oxygen adsorption and incipient oxidation of the Pb(111) surface: A density-functional theory study
Atomic oxygen adsorption and incipient oxidation of the Pb(111) surface: A density-functional theory study
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DOI：
10.1103/physrevb.78.035421
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发表时间：
2007-08
影响因子：
3.7
通讯作者：
Bo Sun;Ping Zhang;Zhigang Wang;S. Duan;Xian-geng Zhao;Xu-Cun Ma;Q. Xue
中科院分区：
文献类型：
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作者：
Bo Sun;Ping Zhang;Zhigang Wang;S. Duan;Xian-geng Zhao;Xu-Cun Ma;Q. Xue
采用密度泛函理论和超原胞方法研究了原子氧在Pb（111）表面的吸附。系统地研究了Pb（111）表面上纯表面和亚表面氧结构的原子和能量性质，得到了广泛的覆盖和吸附位置。fcc和tetra-II网站（见定义的文本）被认为是积极的表面和地下吸附，分别在整个覆盖范围内考虑。表面氧结合能和亚表面氧结合能均随覆盖度的增加而单调增加，且亚表面氧结合能始终高于表面氧结合能，表明表面氧岛（团簇）的形成趋势和亚表面氧吸附的稳定性。原子氧的表面和次表面扩散路径能量学，以及氧从表面渗透到次表面位置的活化屏障，在低和高覆盖率下呈现。对O/Pb（111）体系的电荷分布、晶格弛豫、功函数和电子态密度等性质也进行了详细的研究和讨论。指出在表面氧化过程中O-Pb化学键表现为离子/共价混合键。在这里，离子性的特征是从Pb 6p到O 2 p状态的电荷流，而共价性的特征是Pb 6s（2）“孤对”效应，这是由Pb 6s和O 2 p状态的杂化引起的。
We study the atomic oxygen adsorption on Pb(111) surface by using density-functional theory within the generalized gradient approximation and a supercell approach. The atomic and energetic properties of purely on-surface and subsurface oxygen structures at the Pb(111) surface are systematically investigated for a wide range of coverage and adsorption sites. The fcc and tetra-II sites (see the text for definition) are found to be energetically preferred for the on-surface and subsurface adsorption, respectively, in the whole range of coverage considered. The on-surface and subsurface oxygen binding energies monotonically increase with the coverage, and the latter is always higher than the former, thus indicating a tendency to the formation of oxygen islands (clusters) and the higher stability of subsurface adsorption. The on-surface and subsurface diffusion-path energetics of atomic oxygen, as well as the activation barriers for oxygen penetration from the on-surface to the subsurface sites, are presented at low and high coverage. The other properties of the O/Pb(111) system, including the charge distribution, the lattice relaxation, the work function, and the electronic density of states, are also studied and discussed in detail. It is pointed out that the O-Pb chemical bonding during surface oxidation displays a mixed ionic/covalent character. Here the ionicity is featured by a charge flow from Pb 6p to O 2p states, while the covalency is featured by the Pb 6s(2) "lone pair" effect, which results from hybridization of Pb 6s and O 2p states.