Si原子在CeO_2(111)表面吸附与迁移的第一性原理研究

First Principle Calculation on Adsorption and Diffusion Behavior of Si Atom on CeO_2(111)Surface

为探究Si原子在CeO_2(111)表面吸附的微观行为,采用第一性原理的方法研究了Si原子在CeO_2(111)表面的吸附作用、电子结构和迁移过程,计算了Si原子在CeO2(111)表面的吸附能,最稳定及次稳定吸附位置的电子态密度与电荷密度分布、迁移激活能。计算结果表明:Si原子最易吸附于基底表层的O原子上,其中O桥位(Obri)吸附作用最强,O顶位(Ot)和O三度位(Oh)吸附强度次之。Si原子仅对其最邻近的表层O原子结构影响较大,这与Si原子及其最邻近的O原子间电荷密度重叠程度增强的结果一致。Si原子最易围绕着Ot位从Obri位向Oh位迁移,迁移所需激活能为0.849eV。

In order to research the microscopic behavior of Si atom adsorbed on CeO2（111）surface,the adsorption,electronic structure and diffusion behavior of Si atom on CeO2（111）surface were studied using the first principle method.The adsorption energy was calculated.The electron states density,charge density distribution,diffusion activation energy of the most and sub-stable adsorption sites of Si atom on the CeO2（111）surface were also calculated.The results show that Si atom is most easily adsorbed on the surface layer of O atoms,in which the O bridge site（Obri）has the strongest adsorption,and the adsorption strength at the O top site（Ot）and the O three-fold site（Oh）issecond.Si atom only has a great influence on the structure of the nearest surface of O atoms,which is consistent with the increase of the charge density overlap between the Si atom and its nearest neighbor O atoms.The Si atom most easily diffuses from the Obri site to Ohsite while around the Otsite,and the required activation energy for diffusion is0.849 eV.