苯在Au(100)表面化学吸附的周期性密度泛函理论研究  

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

作　　者：曹梅娟[1] 陈文凯[1] 刘书红[1] 许莹[1] 李俊篯[1] 

机构地区：[1]福州大学化学系,结构化学国家重点实验室,福州350002

出　　处：《物理化学学报》2006年第1期11-15,共5页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(20273013);福建省教育厅科技项目(JA03020)资助~~

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～-184.3kJ·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～-145.3kJ·mol-1、-116.5～-117.0kJ·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键形式连接到表面邻近的Au原子上.Benzene adsorption on Au（100）-3×3 surface has been studied with periodical slab model by Vosko-WilkNusair 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 kl ·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 dτ2 orbital of Au atom. The two carbon atoms in the opposite positions are bonded to the near Au atoms with di-σ bonds.

关 键 词：苯 Au(100) 吸附 密度泛函理论 周期平板模型 

分 类 号：O647.31[理学—物理化学]