Acta Phys. -Chim. Sin. ›› 2006, Vol. 22 ›› Issue (01): 11-15.doi: 10.3866/PKU.WHXB20060103

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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

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