NO在NixAgy (x + y= 13)团簇表面吸附分解的第一性原理研究
First-principles study on the adsorption and desorption of NO on the surface of NixAgy (x + y = 13) clusters

基于第一性原理计算方法，对NixAgy (x + y = 13)团簇的几何结构进行优化后，研究了NO在此类团簇表面不同位置的吸附分解行为，讨论了团簇的束缚能、束缚能的二阶差分、能隙以及吸附前后键长、吸附能、NO分波态密度的变化情况。结果表明，团簇对称性随着Ni的占比变化而变化，稳定性随Ni占比增加而增强，束缚能的二阶差分随着Ni原子的增多呈现奇偶震荡性，NO@NixAgy (x + y = 13)团簇表面吸附行为主要为化学吸附，吸附后N-O键长的变化在0.028？～0.092？之间。对团簇吸附NO的态密度分析发现，吸附后NO的2π*轨道失去电子，1π轨道得到电子，从而导致吸附能的变化。
Based on the first-principles calculation method, the geometrical structures of NixAgy (x + y = 13) clusters were optimized. After changing different number of Ni atoms in clusters, the surface adsorption behavior of NO molecules was studied. Before and after adsorption, the second order difference, the energy gap and the change of bond length were discussed. Calculated results showed that the cluster symmetry was changed with the change of Ni ratio, and the increased stability accompany with the increasing Ni atoms. Obviously, a second order difference of the binding energy exhibits odd and even oscillations with the increase of Ni atoms. Surface adsorptions of these clusters were mainly chemical adsorption. After adsorption, the change range of N-O length was between 0.028？ and 0.091？. The PDOS of NO showed that after adsorption, the 2π* orbits of NO lost electrons and the 1π orbits got electrons, which led to the change of adsorption energy. The different number of Ni atoms in the clusters affected the 1π orbits getting electrons and eventually led to different catalytic properties.