论文部分内容阅读
采用基于密度泛函理论的第一性原理方法和平板模型研究了CH_3SH分子在Cu(111)表面的吸附反应.系统地计算了S原子在不同位置以不同方式吸附的一系列构型,第一次得到未解离的CH_3SH分子在Cu(111)表面顶位上的稳定吸附构型,该构型吸附属于弱的化学吸附,吸附能为0.39 eV.计算同时发现在热力学上解离结构比未解离结构更加稳定,解离的CH_3S吸附在桥位和中空位之间,吸附能为0.75-0.77 eV计算分析了未解离吸附到解离吸附的两条反应路径,最小能量路径的能垒为0.57 eV.计算结果还表明S—H键断裂后的H原子并不是以H_2分子的形式从表面解吸附而是以与表面成键的形式存在.通过比较S原子在独立的CH_3SH分子和吸附状态下的局域态密度,发现S—H键断裂后S原子和表面的键合强于未断裂时S原子和表面的键合.
The adsorption of CH_3SH molecules on Cu (111) surface was investigated by the first-principles method and the plate-plate model based on density functional theory. A series of configurations of S atoms adsorbed in different ways at different positions were systematically calculated. The first The stable adsorption configuration of the un-dissociated CH_3SH molecule on the top of Cu (111) surface was obtained, which is a weak chemisorption with an adsorption energy of 0.39 eV. It was also found that the thermodynamically dissociative structure ratio The dissociative structure is more stable. The dissociated CH_3S is adsorbed between the bridge site and the vacancy. The adsorption energy is 0.75-0.77 eV. The energy barrier of the minimum energy path is calculated and analyzed for two reaction paths that are not dissociatively adsorbed to the dissociative adsorption Is 0.57 eV.The calculated results also show that the H atom after the S-H bond cleavage does not desorb from the surface in the form of H 2 molecule but exists as a bond with the surface. By comparing the S atoms in the independent CH 3 SH molecule and the adsorption It is found that the bond between the S atom and the surface after S-H bond cleavage is stronger than the bond between the S atom and the surface without cleavage.