【摘要】 用密度泛函理论研究了氧原子的吸附对于Ag（100）表面结构和电子态的影响.通过PAW总能计算研究了p（1×1）、c（2×2）和(2^1/2×2*2^1/2)R45°等几种原子氧覆盖度下的吸附结构,以及在上述结构下Ag（100）表面的弛豫特性、吸附能量、功函数等一系列物理量.研究表明:在(2^1/2×2*2^1/2)R45°-2O吸附Ag（100）表面的情况下,每格两列就会缺失一列银原子,即产生了缺列再构,这导致了银原子层间的垂直距离的差异和水平位置的偏移.进一步的局域原子态密度计算表明:在Ag（100）表面(2^1/2×2*2^1/2)R45°-2O吸附的结构中,吸附氧原子和衬底银原子层之间的结合主要来源于表层银原子的4d态和吸附氧原子的2p态的强烈的轨道杂化.还模拟计算了在不同偏压和针尖高度的STM图像,为实验工作者研究该表面的STM图像提供了丰富的数据和理论支持.更多还原

【Abstract】 In this article we have investigated the influence of oxygen adsorption on the surface geometry and electronic properties of Ag(100) surface by using the density-functional theory calculations. The total energy calculations based on projector-augmented wave (PAW) method have been preformed to describe the adsorption geometry at several coverages of oxygen adsorption including p(1×1), c(2×2), and (2×22)R45°, and a series of main physical properties at these coverages on Ag(100) surface such as the surface relaxation, adsorption energy, work function and so on. The results presented in this work show that for an Ag(100) (2×22)R45°-2O geometry, the most stable atomic structure is a type of missing-row reconstruction. Eventually, this structural change causes various displacements of surface atoms which have been calculated in this work. The calculations on the local density of states reveal that in the Ag(100) (2×22)R45°-2O geometry the cohesive effect between the adsorbed oxygen atoms and the substrate Ag layer is essentially due to the sufficient Ag4d-O2p orbital hybridization. Finally we have simulated the STM images for several bias-voltages and tip heights, providing experiments with abundant data and theoretical support.更多还原