团簇Ni_3B_2热力学稳定性及其催化性质

Study on thermodynamic stability and catalytic properties of cluster Ni_3B_2

为研究Ni-B体系的微观性质,运用密度泛函理论(DFT)方法,在B_3LYP/Lan12dz水平下对Ni_3B_2团簇构型进行优化,得到8种稳定构型,通过热力学稳定性的分析可知,三重态稳定存在比例要高于单重态。通过对构型的原子间距及键级分析表明,Ni-Ni间距在小于0.240 nm时有利于团簇稳定,原子间距在0.240 nm到0.345nm之间不利于团簇的稳定;B原子近距离(小于0.170 nm)接触有利于团簇稳定,与文献中结论相符。依据前线轨道理论讨论了各构型参与反应能力,单重态能隙差普遍要低于三重态,参与反应能力更强。既能够稳定存在又具有较强参与反应能力的是平面构型4(3)和1(1)。

In order to study the microscopic feature of amorphous system,using density functional theory（DFT） method to optimize the configuration of Ni3B2 clusters under the B3 lyp/lan12 dz level,8 stable configurations were obtained. The existence ratio of triplet stability was higher than that of single heavy state according to the analysis of thermodynamic stability. The atomic spacing and bond-level analysis of the configuration show that Ni-Ni spacing in less than 0.240 nm is advantageous to the stability of clusters. The stability of clusters is unfavorable when the atomic spacing is between 0.240 nm to 0.345 nm. The close distance of B atom（less than 0.170 nm） is advantageous to the stability of clusters,which is consistent with the conclusions of the literature. According to the theory of front-line orbit,the response ability of each configuration is discussed.The single heavy state gap difference is generally lower than that of the triple state and therefore,the reaction ability is stronger. The Planar configuration 4（3）and 1（1）are both stable and have strong ability to participate in the reaction.