物理化学学报 >> 2010, Vol. 26 >> Issue (05): 1378-1384.doi: 10.3866/PKU.WHXB20100523

量子化学及计算化学 上一篇    下一篇

CO在α-U(001)表面的吸附

李赣, 罗文华, 陈虎翅   

  1. 表面物理与化学国家重点实验室, 四川 绵阳 621907; 中国工程物理研究院, 四川 绵阳 621900
  • 收稿日期:2009-10-26 修回日期:2010-01-19 发布日期:2010-04-29
  • 通讯作者: 李赣 E-mail:2002ligan@sina.com

CO Adsorption on α-U(001) Surface

LI Gan, LUO Wen-Hua, CHEN Hu-Chi   

  1. National Key Laboratory for Surface Physics and Chemistry, Mianyang 621907, Sichuan Province, P. R. China; China Academy of Engineering Physics, Mianyang 621900, Sichuan Province, P. R. China
  • Received:2009-10-26 Revised:2010-01-19 Published:2010-04-29
  • Contact: LI Gan E-mail:2002ligan@sina.com

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摘要：

采用密度泛函理论中的广义梯度近似, 计算了CO在α-U(001)表面的吸附、解离和扩散. 结果表明: CO分子以CU3OU2构型化学吸附在α-U(001)表面, 吸附能为1.78-1.99 eV; 吸附后表层U原子向上迁移, 伴随着褶皱的产生; CO分子与表面U原子的相互作用主要是U原子的电子向CO分子最低空轨道2π*转移, 以及CO2π*/5σ/1π-U6d轨道间杂化而生成新的化学键; CO解离吸附较分子吸附在能量上更为有利, h1(C)+h2(O)和h1(C)+h1(O)(h:空位)解离态吸附能分别为2.71和3.08 eV; 近邻三重穴位之间C、O原子的扩散能垒分别为0.57 和0.14 eV, 预示O原子较C原子更易在U(001)表面扩散迁移.

关键词: 密度泛函理论, α-U(001)表面, CO, 吸附

Abstract:

The adsorption, dissociation, and diffusion of CO on the α-U(001) surface were studied using density functional theory with the generalized gradient approximation (GGA). The calculation results show that a CU3OU2-type molecular chemisorption of CO is favored with adsorption energies of 1.78-1.99 eV. The U atoms of the surface layer are found to move upwards after adsorption coupled with a rumpling of the surface layer. The interaction between the U atoms and a CO molecule results mainly from the population of the CO 2π* LUMO by U electrons and the CO 2π*/5σ/1π-U 6d orbital hybridization. Dissociative adsorption is energetically more favored than molecular adsorption with adsorption energies of 2.71 and 3.08 eVfor the h1(C)+h2(O) and h1(C)+h1(O) (h: hollowsite) dissociative configurations, respectively. The diffusion barriers of C and O atoms between two adjacent threefold hollow sites are found to be 0.57 and 0.14 eV, respectively, which indicates that the on-surface diffusion ofO atoms is more easily achieved than that of C atoms.

Key words: Density functional theory, α-U(001) surface, Carbon monoxide, Adsorption