中文摘要：

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CH3SH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CH3SH分子在Cu（111）表面项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O．39eV．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CH3S吸附在桥位和中空位之间，吸附能为0．75-0．77eV．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0．57eV．计算结果还表明S—H键断裂后的H原子并不是以H2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CH3SH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．

英文摘要：

The interaction of methanethiol （CH3SH） molecules with the Cu（111） surface was investigated using a first-principles method based on density functional theory, and a slab model. A series of possible adsorption configurations constructed using S atoms on different sites with different tilt angles were studied. It was found for the 5.rst time that the non-dissociative molecular adsorption of CH3SH on the Cu（111） surface with the S atom sitting on the top site belongs to the weak chemisorption, and the adsorption energy is 0.39 eV. After the dissociation of the S-- H bond, the S atom is located at the bridge site, with a small shift toward the hollow site. The dissociative adsorption structure is thermodynamically more stable than the intact one, and the adsorption energy is 0.75-0.77 eV. Two reaction pathways have been studied for the transition from non-dissociative adsorption to dissociative adsorption, and the activation energy barrier along the minimum energy path is 0.57 eV. The results of the calculations indicated that the released H atom prefers to form a bond with the copper surface, rather than desorbing in the H2 molecular form. Comparing the local density of states of S atoms in the single CH3SH, CH3SH/ Cu（111）, and CH3S/Cu（111） structures, we found that the bonding between the S atoms and the substrate is much stronger in the dissociated adsorption states.