硫在Fe(111)面吸附的密度泛函研究

Density functional theory study on sulfur adsorption on Fe(111) surface

采用基于密度泛函理论的第一性原理方法,系统研究了不同覆盖度下硫在Fe(111)表面的吸附构型和吸附特性,计算并分析了硫在Fe(111)表面的吸附能、电荷密度、分波态密度、电荷布局、电子局域化函数等数据.研究结果表明:S在Fe(111)面的H位吸附最稳定,并且吸附能随着覆盖度的增加而增加.另外,电子态密度、电子局域化函数和布局分析表明Fe、S之间呈较弱的共价键,这种作用力主要是Fe的3d轨道和S的3p轨道杂化所贡献,而随着覆盖度的增加,Fe、S之间的作用力逐渐减弱,这可能是由于S原子之间的排斥力减弱了Fe、S之间的作用.S在Fe(111)、Fe(110)和Fe(100)这三个晶面上吸附情况的对比分析发现,S与Fe(111)表面的相互作用最强,Fe(100)面次之,而Fe(110)面最弱.

The adsorption configuration and property of atomic sulfur on the Fe（111） surface have been systematically investigated through first principles method based on the Density Functional Theory （DFT） in wide ranges of coverage, and the data on adsorption energy, charge density, partial electron density of states（PDOS）, charge population and electron localized functions（ELF） of sulfur on Fe（111） have been calculated and analyzed. The calculation results indicate that the hollow site is the energetical- ly favorable site for sulfur adsorption on Fe（lll）, and the adsorption energy increases with the increas- ing atomic sulfur coverage. Moreover, the analyses of electron density of states（DOS）, ELF and charge population reveal that the atomic sulfur and iron atoms are combined by a rather weaker covalent bond, this interaction is largely due to the hybridization of Fe 3d orbital and S 3p orbital. With the increasing of coverage, such force between iron atoms and sulfur gradually decreases, which is likely to be driven by the repulsion between sulfur atoms. By comparative analysis of atomic sulfur adsorption on Fe（111）,Fe（110） and Fe（100） surfaces, it is found that the interactive force between atomic sulfur and Fe（111） surface is strongest, the Fe（100） surface comes second, the Fe（ll0） surface occupies last place.