Pd_n(n=1-7)团簇及其与甲烷相互作用的密度泛函理论研究

A DFT Study of Pd_n(n=1-7) Clusters and Their Interactions with CH4 Molecule

用密度泛函理论(DFT)的B3LYP方法,对Pd_n(n=1-7)团簇的几何结构、振动频率及其与甲烷分子间的相互作用进行了理论研究.结果表明,随着Pd原子数增多,团簇结构对团簇大小的依赖性减弱,结构参数向金属晶体趋近.在Pd_n(n=1-7)团簇上,甲烷的表面吸附作用较弱.Pd_2CH_4中,甲烷受到两个Pd原子的活化作用,活化程度增强,吸附能增大.在Pd_nCH_4(n=1,3-7)体系中,甲烷的吸附能随着团簇模型的增大而减小,趋近于其在金属晶面上的吸附能.

The geometric configurations, vibrational frequencies of Pdn（n=1-7） clusters and their interactions with a CH4 molecule were studied using the DFT/B3L YP method. Increasing the total number of palladium atoms made the cluster less size-dependent and structural parameters approach to the bulk solid. Methane adsorption on Pdn（n=1-7） clusters was very weak. Methane was activated by Pd2 cluseter, activation and adsorption energy were aggrandized. With increasing cluster size, the interaction of molecular-surface in PdnCH4 （n=1,3-7） clusters became weak, and the adsorption energy approached to that on the bulk metal.