氯原子在Cu(111)表面的吸附结构和电子态

密度泛函理论(DFT)总能计算研究了不同覆盖度下氯原子在Cu(111)表面的吸附结构和表面电子态。计算结果表明，清洁Cu(111)表面自由能 为15.72 ，表面功函数φ为4.753eV。在1/4ML和1/3ML覆盖度下，每个氯原子在Cu(111)表面fcc谷位的吸附能分别等于3.278eV/atom和3.284eV/atom。在1/2ML覆盖度下，两个紧邻氯原子分别吸附于fcc和hcp谷位，氯原子的平均吸附能为2.631eV/atom。在1/3ML覆盖度下，fcc和hcp两个位置每个氯原子吸附能的差值约为2meV/atom，与正入射X光驻波实验结合蒙特卡罗方法得到结果(<10meV/atom)基本一致。在1/4ML、1/3ML和1/2ML覆盖度下，吸附后Cu(111)表面的功函数依次为5.263eV、5.275eV和5.851eV。吸附原子和衬底价轨道杂化形成的局域表面电子态位于费米能级以下约1.2eV、3.6eV和4.5eV等处。吸附能和电子结构的计算结果表明，氯原子间的直接作用和表面铜原子紧邻氯原子数目是决定表面结构的两个重要因素。

The Geometry Structure and Electronic States of Chlorine on Cu(111) Surface

In this paper first principles calculations were performed on the geometric structures and adsorption properties of chlorine on Cu(111) surface at the different coverage by using USPP methods. The free surface energy of clean Cu(111) surface is about to be 15.72 , and the work function was estimated to be 4.753eV. At the coverage of 1/4ML, Chlorine atoms adsorbed on the fcc and hcp hollow sites. The average adsorption energy was calculated to be 3.278eV/atom, comparing with 3.284eV/atom and 2.631eV/atom at the coverage of 1/3ML and 1/2ML respectively. In the coverage of 1/3 ML, the adsorption energy distance between fcc and hcp sites was predicted to be about 2 meV/atom, which was in good agreement with the normal-incidence x-ray standing waves experiences combined with Monte Carlo simulations. The adsorption of Chlorine on Cu(111) surface yields the hybridization between surface Cu atoms and Chlorine atoms, and generates the localized surface states at -1.2eV,-3.6eV and -4.5eV relative to Fermi energy.