甲醇在Ir(111)表面吸附的密度泛函理论研究

Density Functional Theory Study of Methanol 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CH3OH分子在Ir(111)表面top,bridge,fcc和hcp位的吸附模型进行了构型优化,对体系的吸附能、O-H键、C-O键和-CH3键等振动频率进行了计算,并对电子态密度(DOS)进行了分析.计算结果表明top位是比较有利的吸附位,但是吸附能较小,吸附后甲醇分子构型未发生较明显的变化.通过对吸附前后甲醇分子振动频率分析,发现甲醇吸附后O-H键比C-O键红移大,说明甲醇解离时O-H键比C-O键活化程度高.通过DOS分析发现甲醇主要是π轨道参与了成键.

The first-principles density functional theory（DFT） and the periodic slab model are used to investigate the adsorption of methanol on Ir（111） surface.The adsorption energies,structures,vibrational frequencies and density of states are calculated.The results show that the favorite adsorption occurs at the top site.The adsorption energies of CH3OH are small.The molecule configuration of methanol is not changed significantly after adsorption.The vibration frequency of the O-H bond has larger redshift than that of the C-O bond,which indicates that the decomposition of methanol is more active via O-H bond scission than C-O bond scission.According to the density of states analysis,the π orbital of methanol is mainly involved in bonding.