周期性密度泛函理论研究NO在Cu_2O(111)表面上的吸附  

A DFT Study on the Chemisorption of NO on Cu_2O(111) Surface

作　　者：孙宝珍[1] 陈文凯[1] 刘书红[1] 曹梅娟[1] 陆春海[2] 许莹[1] 

机构地区：[1]福州大学化学系,福州350002 [2]成都理工大学核技术与自动化工程学院,成都610059

出　　处：《无机化学学报》2006年第7期1215-1221,共7页Chinese Journal of Inorganic Chemistry

基　　金：福建省教育厅项目(No.JA03020);福州大学科技发展基金(No.2005-XQ-03);福建省重大专项基金(No.2005HZ01-2-6)资助

摘　　要：运用广义梯度密度泛函理论(GGA)的PBE方法结合周期平板模型,在DND基组下,研究了NO以N端和O端两种吸附取向在Cu2O(111)非极性表面上的吸附。通过对不同吸附位置的吸附能和几何构型参数的计算和比较发现:表面上配位不饱和的铜离子(CuCUS)为活性吸附位;NO的N端吸附比O端吸附更为有利,N端吸附时吸附能可达到113.5kJ·mol-1,而O端情况下只有39.7kJ·mol-1;NO倾斜吸附在Cu2O(111)表面上,O端吸附时倾斜度更大。在两种吸附取向情况下,N-O键的伸缩振动频率都发生了较大的红移,N端吸附情况下红移150cm-1,O端时红移330cm-1。前线轨道分析表明,Cu与NO间的吸附作用主要是Cu的d轨道和NO的π*轨道间的相互作用。表面弛豫的计算表明,Cu2O(111)面的弛豫对O端吸附方式产生较大影响,考虑表面弛豫时O端吸附为很弱的化学吸附(吸附能为39.7kJ·mol-1),而没有考虑弛豫时吸附能为60.5kJ·mol-1。The adsorption of NO molecule on Cu2O（111） non-polar surface has been studied with periodic slab model by Perdew-Burke-Ernzerh approach of GGA within the framework of density functional theory. Two molecular orientations, N- and O-down, over different adsorption sites, Cucas, CuCSA, OsuF and OSUB of the Cu2O（111） surface have been considered. The optimized results indicate that the N-down adsorption models are sable than the Odown ones. The adsorption energy for the N-down mode over Cucts site is 113.5 kJ@mol^-1 while the corresponding value for the latter mode is 39.7 kJ-mol^-1. Upon adsorption on the Cu^＋ cation, the NO molecules forms a bent Cu^＋ -NO bond, and the tilted angles are different at the two orientations. The N-O stretching frequencies for both orientations are significantly red-shifted upon coordination. The frontier molecular orbitals analysis indicates that, for N-down and O-down orientation, the interaction between the adsorbed molecule and the substrate mainly arises from the anti-bonding π orbital of NO and the d orbital of copper atom. Moreover, the relaxation should be considered because of the effects of the geometry of Cu2O（111） surface upon the adsorption geometries and the binding energies of O-down adsorption.

关 键 词：密度泛函理论 周期平板模型 NO 吸附 Cu2O(111)非极性表面 

分 类 号：O641.121[理学—物理化学]