甲氧基在Ir(111)表面吸附的密度泛函理论研究

Density functional theory study of methoxy adsorption on Ir(111)surface

本文采用第一性原理和周期平板模型相结合的方法,对甲氧基在Ir(111)表面top,bridge,fcc和hcp位的吸附模型进行了构型优化、能量计算、Mulliken电荷布居分析以及差分电荷密度计算.结果表明,甲氧基通过氧原子与金属表面相互作用时,垂直吸附在fcc位是最有利的吸附构型,吸附能为2.26eV,此时电子从金属表面向甲氧基转移.吸附过程中C-O键振动频率发生红移,表明在该表面C-O键容易被活化.结合差分电荷密度分析表明,吸附时CH3O中氧的2p原子轨道和铱的dz2原子轨道相互作用形成σ键.

The first-principles density functional theory （DFT）and the periodic slab model are used to investigate the adsorption of methoxy on Ir （111）surface.The adsorption energies,equilibrium geome-try,Mulliken charges and charge density difference are calculated.The results show that methoxy ad-sorbs at the fcc site vertically via the oxygen atom with the adsorption energy of 2.26 eV.The electronic charges transfer from Ir to methoxy species.The stretching frequency for C-O bond of CH3 O has a red shift,which indicates that the C-O bond is easy to be activated.According to the analysis of the charge density difference,the 2p atomic orbits of oxygen interact with the dz2 orbit of iridium atoms to form theσorbit in bonding.