NO双分子和二聚体与Cu2作用的理论计算

采用密度泛函理论(DFT)中的B3LYP方法，在Lanl2DZ基组下，对NO双分子和二聚体与铜原子簇相互作用的结构进行了研究. 结果表明，NO可以在铜表面相邻的两个铜原子上形成稳定的双分子吸附和二聚体吸附，而在双分子吸附形式中NO以氮原子吸附在铜上的构型最稳定，且顶点吸附的稳定性不如非顶点吸附形式.在二聚体吸附形式中， N－N键被加强，而N－O键被削弱的程度大于双分子吸附形式，说明二聚体的形成有利于NO在金属铜表面的直接分解.同时电荷布居分析表明，单重态的二聚体与铜作用时，铜原子上的平均电荷达到0.66 e,说明在这种吸附形式中铜被离子化的倾向较大，而且这种吸附形式最有利于NO的分解.这些结果说明NO经二聚体形式在铜表面直接催化分解是可行的.

Theoretical Study on the Interaction of Two NO Molecules and Dimers with Cu2

The interaction of two NO molecules and NO dimers with Cu2 has been studied at B3LYP/Lanl2DZ level. The results show that the NO molecules and dimers can be stably adsorbed on the adjacent Cu atoms on the copper surface. However, the structure of NO adsorbed on Cu atom with N-down ward is more stable than any other structure in the NO co-adsorption models, and the NO atop adsorption is less stable than the other. On the other hand, the N－N bond is strengthened, while the N-O bond is weakened in the NO dimer adsorption models. It indicates that the formation of NO dimer is favorable to the NO direct decomposition on the copper surface. The Mülliken population analysis shows that the average charge on Cu is 0.66 e, when the singlet state dimer interacts with the copper. It suggests that the bond between the singlet state dimer and the Cu atom is more ionic, and that the N-O bond is more reactive in singlet state dimer. The calculation results reasonably indicate that NO can be directly decomposed via the dimer configurations on the copper surface.