物理化学学报 >> 2006, Vol. 22 >> Issue (01): 11-15.doi: 10.3866/PKU.WHXB20060103

研究论文 上一篇    下一篇

苯在Au(100)表面化学吸附的周期性密度泛函理论研究

曹梅娟; 陈文凯; 刘书红; 许莹; 李俊篯   

  1. 福州大学化学系, 结构化学国家重点实验室, 福州 350002
  • 收稿日期:2005-05-16 修回日期:2005-06-28 发布日期:2006-01-15
  • 通讯作者: 陈文凯 E-mail:qc2008@fzu.edu.cn

A Density Functional Theoretical Study on the Chemical Adsorption of Benzene on Au(100) Surface

CAO Mei-juan; CHEN Wen-kai; LIU Shu-hong; XU Ying; LI Jun-qian   

  1. State Key Laboratory of Structural Chemistry, Department of Chemistry, Fuzhou University, Fuzhou 350002, P. R. China
  • Received:2005-05-16 Revised:2005-06-28 Published:2006-01-15
  • Contact: CHEN Wen-kai E-mail:qc2008@fzu.edu.cn

摘要: 采用局域密度泛函理论(LDA)的VWN方法, 结合周期平板模型, 在DNP基组下, 研究了苯分子在Au(100)面的吸附情况. 构型优化的结果表明, 苯分子在穴位吸附活性最高, 吸附能为-184.8~-184.3 kJ•mol-1, 苯环发生扭曲, C—C键明显拉长, 出现了介于苯和1,4-环己二烯之间的船状构型, 船头的2个C原子从sp2杂化重新进行sp3杂化. 苯分子在桥位和顶位的吸附活性较低, 吸附能分别为-156.7~-145.3 kJ•mol-1、-116.5~-117.0 kJ•mol-1, 苯分子构型有稍微的改变. 轨道分析的结果还表明, 吸附之后苯分子的轨道简并度降低, 苯分子的LUMO轨道和邻近Au原子的dz2轨道叠加比较好, 两个对位的C原子以双σ形式连接到表面邻近的Au原子上.

关键词: 苯, Au(100), 吸附, 密度泛函理论, 周期平板模型

Abstract: Benzene adsorption on Au(100)-3×3 surface has been studied with periodical slab model by Vosko-Wilk-Nusair LDA functional under double numeric basis with polarization functions. The results of geometry optimization indicate that the hollow site in the highest coordination is energetically active for benzene adsorbed on Au(100) surface, and the adsorption energy is -184.8~-184.3 kJ•mol-1. The benzene ring has been distorted, and the C—C bond has a considerable elongation. Two opposite carbon atoms are involved in the adsorption process leading to a rehybridization of the two carbon atoms from sp2 to sp3, which makes the adsorbate state intermediate between benzene and 1,4-cyclohexadiene. The benzene adsorbed in the bridge and top positions is found to be energetically less favorable, and the adsorption energies are respectively -156.7~-145.3 kJ•mol-1 and -116.5~-117.0 kJ•mol-1. The geometry of benzene has a slight elongation. The molecular orbital analysis also indicates that the degenerate frontier molecular orbitals lose their degeneracy with decrease of symmetry. The LUMO of benzene has a good overlap with the dz2 orbital of Au atom. The two carbon atoms in the opposite positions are bonded to the near Au atoms with di-σ bonds.

Key words: Benzene, Au(100), Adsorption, Density functional theory, Periodic slab mode