甲氧基在Rh(111)表面吸附的密度泛函研究

A DFT study on the adsorption of methoxy on the Rh(111) surface

采用密度泛函理论(DFT)的B3LYP方法,以原子簇Rh13(9,4)为模拟表面,在6-31G(d,p)与Lanl2dz基组水平上,对甲氧基在Rh(111)表面的四种吸附位置(fcc、hcp、top、bridge)的吸附模型进行了几何优化、能量计算、Mulliken电荷布局分析以及前线轨道的计算。结果表明,当甲氧基通过氧与金属表面相互作用时,在bridge位的吸附能最大,吸附体系最稳定,在top位转移的电子数最多;吸附于Rh(111)面的过程中C—O键被活化,C—O键的振动频率发生红移。

The interaction of methoxy（CH3O·） with Rh（111） surface was studied by hybrid-method B3LYP based on density functional theory.The Lanl2dz basis set for Rh atom and the 6-31G（d,p） basis set for O,C and H atoms were used.The Rh13（9,4） cluster was used to simulate the surface.Four typical adsorption sites,top,hcp,bridge and fcc sites,were investigated theoretically and the information about the preferred adsorption geometry and energy of CH3O· species was extracted.The results show that the bridge site is more favorable than the other adsorption sites and the amount of electronic charge transferred from Rh to methoxy species is higher than those on the other sites when CH3O· is bonded to the surface via the oxygen atom.C—O bond is activated and its stretching frequency is red shifted in the process of C—O bond adsorption on Rh（111） surface.