H_2S在Fe(100)面吸附的第一性原理研究

First principles calculation of adsorption for H_2S on Fe(100) surface

基于密度泛函理论第一性原理,在广义梯度近似下,研究了表面覆盖度为0.25ML(monolayer)时硫化氢分子在Fe(100)面吸附的结构和电子性质,并与单个硫原子吸附结果进行了对比.结果表明:硫化氢分子吸附在B2位吸附能最小为1.23eV,最稳定,B1位吸附能最大为0.01eV,最不稳定;并对硫化氢分子在B1位和B2位吸附后的电子态密度进行了分析,也表明了吸附在B2位稳定,且吸附在B2位后硫化氢分子几何结构变化不大;将硫化氢中硫原子吸附与单个硫原子吸附的电子性质进行了比较,发现前者吸附作用非常微弱;同时对吸附后的Fe(100)面进行了对比,单个硫原子吸附的Fe(100)面电子态密度出现了一系列峰值且离散分布,生成了硫化亚铁,表明在硫化氢环境下,主要是硫化氢析出的硫原子发生了吸附.

In contrast to the results of sulfur atom adsorption, the adsorption of hydrogen sulfide on the Fe（100） surface has been studied using first principles method, which is based on the density functional theory （DFT）. The structures, electronic properties were calculated by the generalized gradient approximation （GGA） for the coverage of 0.25 monolayer （ML）. The results show that the H2S adsorbed on B2 site is stable and the adsorption energy is -1.23 eV and the structure of H2S is little changed. While the density of states （DOS） for the adsorption of hydrogen sulfide in the most unstable state after the adsorption at B1 and most stable adsorption at the site of B2 are analyzed. We have compared, under same conditions, the electronic properties of the sulfur atoms of the adsorbed hydrogen sulfide and a single sulfur atom adsorbed on Fe（100） surface. The adsorption effect is very weak for sulfur atoms in adsorbed hydrogen sulfide. At the same time, the density of states for the adsorption of Fe（100） surface was studied comparatively, and we found that the sulfur atom adsorption on Fe（100） showed a series of peaks that have discrete distributions generated by ferrous sulfide. It shows that the adsorption is given by sulfur atoms instead of molecules of hydrogen sulfide.