团簇Mo_(3)S_(4)的极化率、电子自旋密度及催化性质

Polarizability,electron spin density and catalytic properties of cluster Mo_(3)S_(4)

为了探究微观状态下,团簇Mo_(3)S_(4)内部电子的变化情况及其催化机理,基于密度泛函理论的B3LYP方法对团簇Mo_(3)S_(4)的几何构型进行优化和频率计算,得到一、三重态各4种优化构型。文中计算并讨论了该团簇的极化率、能隙差以及Mo、S原子和各原子间的电子自旋密度,研究结果表明:构型1(3)的极化率各向异性不变量最小,说明构型1(3)对于外场的响应最弱,受外场影响的难度更大。当受外场作用时重态构型的电子云发生形变程度小于除构型2(1)以外的一重态构型,其中构型2(1)的极化率最小,原子间的相互作用力最强,结构最紧凑且最不易发生变形。比较三重态构型的电子自旋密度发现,构型1(3)的外围电子自旋密度分布均匀,内部原子间成键强度相近,其构型稳定性优于其他三重态构型。在催化反应中,构型4(1)的能隙差最小,化学反应能力最大,催化活性最好。

In order to explore the change of electrons in cluster Mo_(3)S_(4) and its catalytic mechanism in the microscopic state,the B3LYP method based on density functional theory optimized the geometric configuration and frequency calculation of the cluster Mo_(3)S_(4),and obtained 4 optimized configurations for the first and triplet states.The polarizability,energy gap difference and the electron spin density between Mo and S atoms and each atom of the cluster were calculated and discusses.The research results show that the polarizability anisotropy invariant of configuration 1(3) is the smallest,which indicates that configuration 1(3) has the weakest response to the external field,and it is more difficult to be affected by the external field.When subjected to an external field,the electron cloud of the heavy configuration is less deformed than that of the singlet configuration except for configuration 2(1).Configuration 2(1) has the smallest polarizability,the strongest interaction between atoms,the most compact structure and the least deformation.Comparing the electron spin density of the triplet configuration,it is found that the outer electron spin density of configuration 1(3) is uniformly distributed,the bonding strength between internal atoms is similar,and its configuration stability is better than other triplet configurations.In the catalytic reaction,configuration 4(1) has the smallest energy gap difference,the largest chemical reaction capacity and the best catalytic activity.