Ni(110)-p2mg(2×1)-CO表面的几何结构和电子态

Geometric Structures and Electronic States of Ni(110)-p2mg(2×1)-CO Surface

利用密度泛函理论(DFT)总能计算研究了Ni(110)-p2mg(2×1)-CO表面的原子结构和电子态.计算结果表明:CO分子吸附于该表面的短桥位附近,分子吸附能为1.753eV,CO分子的键长dC—O为0.117nm,分子与表面竖直方向的夹角为20.0°,碳原子和短桥位中点的连线与竖直方向的夹角为20.9°;吸附的CO分子内原子间的伸缩振动频率为1876和1803cm-1.态密度研究结果表明吸附作用主要来自CO分子π、σ轨道与衬底d轨道间的杂化作用.CO分子σ轨道和衬底表面镍原子dxz轨道杂化形成的表面电子态主要位于费米能以下-10.4至-8.8eV和-7.4至-5.1eV范围内.σ和dxz轨道间的杂化作用可能是形成p2mg表面对称性的重要因素之一.

First-principles calculations were performed to determine the geometric structure and electronic states of Ni（110）-p2mg（2×1）-CO surface.We found that the CO molecules were adsorbed onto nearby short bridge sites.The molecular adsorption energy was calculated to be 1.753 eV.The C—O bond length was about 0.117 nm.The angle between the bond of the CO molecule and the vertical of the Ni（110） surface was 20.0°.The tilt angle of the direction linking the carbon and the center of the short bridge was 20.9°.The stretch vibration frequencies between the carbon and the oxide atoms of an adsorbed CO molecule was 1876 and 1803 cm-1.The density of states suggests that the chemical interaction between the CO molecules and Ni atoms was mainly caused by hybridization between molecular orbitals π,σ and d orbitals.Surface p2mg（2×1） reconstruction may be attributed to the hybridization between σ molecular orbitals of CO and dxz orbitals of nickel atoms.Surface electronic states resulting from an interaction between σ molecular orbitals of CO and dxz orbitals of nickel atoms were localized below the Fermi energy（0 eV） from-10.4 to-8.8 eV and from-7.4 to-5.1 eV.