摘要
用密度泛函理论(DFT)的总能计算研究了金属Ir(110)表面结构以及氧原子的吸附状态.计算得到Ir(110)-(1×1)的外层表面间的弛豫分别是-13.3%(△d12/d0)和+6.1%(△d23/d0),表面能σ=175meV-2,功函数Φ=5.22eV;相应的Ir(110)-(1×2)缺列再构表面的△d12/d0=-9.7%,△d23/d0=-2.4%,表面能为169meV/2,Φ=5.33eV.研究Ir(110)-(1×1)和(1×2)再构表面氧吸附,发现各吸附位置的吸附能值均为正值,表明吸附为放热反应,且氧原子最有可能吸附在短桥位(shortbridgesite,SB).同时我们还模拟计算Ir(110)-(1×2))缺列再构表面和氧吸附再构表面的扫描隧道显微镜(STM)图像并记录STM针尖的起伏变化,结果显示表面吸附氧的位置远高于{001}方向的铱原子列,但是在STM形貌图上氧原子基本上没有凸起.
We have performed the density-functional theory total-energy calculations on the structures and oxygen adsorption properties of Ir（110） surfaces.The calculated atomic relaxations of Ir（110）-（1×1） surface have been determined to be-13.3%（△d12/d0） and ＋6.1%（△d23/d0）,respectively.Meanwhile the related surface energy and workfunction were calculated to be 175 meV/-2 and 5.22 eV,respectively.In the case of Ir（110）-（1×2） missing-row reconstructed surface,these quantities have been calculated to be -9.7 %（△d12/d0）,-2.4%（△d23/d0）,169 meV -2（σ）,and 5.33 eV（Φ）.The detailed calculations for oxygen adsorption on Ir（110）-（1×1） and（1×2） missing-row reconstructed surfaces have revealed that the adsorption energies in these cases are positive in respect to O2 molecule and the preferred adsorption site of atomic oxygen is the short bridge site（SB） exactly.The STM topographical images of clean Ir（110）-（1×2） missing-row reconstructed and oxygen-adsorbed surfaces have also been simulated.The simulations showed that the missing-row reconstruction yielded a remarkable hollow in the STM morphology.While in the case of Ir（110）-（1×2）/O-SB surface,the height of adsorbed oxygen atoms in the STM topography is very small.This observation has been discussed and explained by considering the specific features of surface oxygen atoms.
出处
《中国科学：物理学、力学、天文学》
CSCD
北大核心
2011年第9期1080-1088,共9页
Scientia Sinica Physica,Mechanica & Astronomica
基金
国家自然科学基金资助项目(批准号:11074217)
