物理化学学报 >> 2010, Vol. 26 >> Issue (08): 2267-2273.doi: 10.3866/PKU.WHXB20100828

催化和表面结构 上一篇    下一篇

氢原子在Be(0001)表面吸附的密度泛函理论研究

宁华, 陶向明, 王芒芒, 蔡建秋, 谭明秋   

  1. 浙江大学物理系, 杭州 310027
  • 收稿日期:2010-01-14 修回日期:2010-03-12 发布日期:2010-07-23
  • 通讯作者: 谭明秋 E-mail:mqtan@zju.edu.cn
  • 基金资助:

    浙江省教育厅科研项目(Y200804278)和长江学者和创新团队发展计划(IRT0754)资助

Density Functional Theory Study on Hydrogen Adsorption on Be(0001) Surface

NING Hua, TAO Xiang-Ming, WANG Mang-Mang, CAI Jian-Qiu, TAN Ming-Qiu   

  1. Department of Physics, Zhejiang University, Hangzhou 310027, P. R. China
  • Received:2010-01-14 Revised:2010-03-12 Published:2010-07-23
  • Contact: TAN Ming-Qiu E-mail:mqtan@zju.edu.cn
  • Supported by:

    The project was supported by the Research Project of Department of Education of Zhejiang Province, China (Y200804278) and Programfor
    Changjiang Scholars and Innovative Research Teamof the Ministry of Education of China (IRT0754).

摘要:

采用第一性原理的密度泛函理论研究单个氢原子和多个氢原子在Be(0001)表面吸附性质. 给出了氢吸附Be(0001)薄膜表面的原子结构、吸附能、饱和度、功函数、偶极修正等特性参数. 同时也讨论了相关吸附性质与氢原子覆盖度(0.06-1.33 ML)的关系. 计算结果表明: 氢原子的吸附位置与覆盖度之间有强烈的依赖关系, 覆盖度低于0.67 ML时, 氢原子能量上易于占据fcc或hcp的中空位置; 覆盖度为0.78 ML时,中空位与桥位为氢原子的最佳吸附位; 覆盖度在0.89到1.00 ML时, 桥位是氢原子吸附能量最有利的位置; 以上覆盖度中Be(0001)表面最外层铍原子的结构均没有发生明显变化. 当覆盖度为1.11-1.33 ML, 高覆盖度下Be(0001)表面的最外层铍原子部分发生膨胀, 近邻氢原子渗入到铍表面次层, 氢原子易于占据在hcp和桥位. 吸附结构中的氢原子比氢分子中的原子稳定. 当覆盖度大1.33 ML时, 计算结果没有发现相对于氢分子更稳定的吸氢结构. 同时从分析偶极修正和氢原子吸附垂直高度随覆盖度的变化关系判断氢覆盖度为1.33 ML时, 在Be(0001)表面吸附达到饱和.

关键词: 密度泛函理论, Be(0001)表面, 氢原子吸附, 吸附能

Abstract:

We report on density functional theory (DFT) total-energy calculations within the generalized gradient approximation for the adsorption of hydrogen onto Be(0001) surface. To investigate the atomic geometries and stability with different hydrogen coverages for this system, we changed the atomic hydrogen coverage from 0.06 to 1.33 monolayer (ML) using various surface supercell geometries. The calculations showed that the adsorption sites have a strong dependence on hydrogen coverage. The adsorbates mainly occupied fcc and hcp hollow sites below 0.67 ML. At 0.78 ML the hydrogen atoms were adsorbed on hollow and bridge sites while for the higher coverage range (ca 0.89-1.00 ML) the hydrogen atoms were adsorbed onto the tilted bridge sites, i.e., a bridge site with a small deviation towards the hollow position. From 1.11 to 1.33 ML, the adsorbed hydrogen atoms were located at hcp and bridge sites, and some Be surface atoms were expanded. All these adsorption configurations were found to be energetically favorable with a H2 reference point fixed on H2 molecule. Further total-energy calculations based on a p(3×3) geometry did not revealed any stable or energetically favorable adsorption geometry versus the H2 molecule beyond a hydrogen coverage of 1.33 ML.

Key words: Density functional theory, Be(0001) surface, Hydrogen adsorption, Adsorption energy

MSC2000: 

  • O641