团簇Mo_(3)S_(4)的电子性质和磁学性质

Electronic and magnetic properties of cluster Mo_(3)S_(4)

基于密度泛函理论研究了团簇Mo_(3)S_(4)的电子性质及磁性,采用LanL2DZ赝势基组和B3LYP方法对初始构型进行优化计算,最终得到8种优化构型.研究结果表明:电子从Mo-4d,Mo-5s和S-3s轨道流向Mo-5p,S-3p和S-3d轨道,比较各原子轨道的布居数变化发现Mo原子的5s和5p轨道的电子流动性更强,对成键的贡献更大,而S原子的3s和3d轨道的电子流动能力相近且3d轨道贡献更小.Mo原子相较于S原子对团簇Mo_(3)S_(4)的总磁矩贡献更大.进一步分析s,p和d轨道对磁性的贡献大小遵循d轨道>s轨道>p轨道,团簇Mo_(3)S_(4)的磁性主要由Mo-4d轨道的自旋向上的α电子贡献.

Transition metal clusters have gradually become one of the key research topics in cluster science.In recent years,molybdenum compounds have developed rapidly in the chemical industry and developed towards multi-polarization,mainly used in catalysts,catalytic activators and lubricants.Molybdenum compounds have strong hydrogen binding energy,and obvious conductivity can be used to prepare high-performance and stable electrocatalysts for hydrogen and oxygen evolution reactions,which is of great significance for sustainable water decomposition technology.Among them,cluster Mo_(3)S_(4)can be used as molecular assisted catalyst to significantly improve the photocatalytic activity of the material and greatly improve the yield of hydrogen.It was found that cluster Mo_(3)S_(4)could be used as an efficient electrocatalyst in electrochemical field.Therefore,it is very necessary to further explore the properties of Mo_(3)S_(4)clusters from the theoretical and experimental aspects.At present,most of the existing studies are from the macroscopic experimental point of view,but the theoretical research is relatively less.In this paper,starting from the cluster Mo_(3)S_(4)model,the local structure and electromagnetic properties are analyzed and studied in order to provide theoretical basis for the theoretical guidance and practical application of the system in the future.Based on density functional theory and topological principles,this paper designs all initial configurations of the cluster Mo_(3)S_(4)in the first and triplet states,and uses the B3LYP quantum level under the LanL2DZ pseudopotential basis set level to perform full parameter optimization and frequency verification on it.Excluding false frequencies and repeated configurations,8 optimized configurations are finally obtained.The results show that the electrons flow from Mo-4d,Mo-5s,S-3s orbitals to Mo-5p,S-3p and S-3d orbitals.Comparing the population changes of each atomic orbital,it is found that the stronger electron mobility of 5s and 5p orbitals of Mo atom contributes more to bonding,while the electron mobility of 3s and 3d orbitals of S atom is similar and the contribution of 3d orbital is smaller.The magnetic moment of Mo atom contributes more to the total magnetic moment of cluster Mo_(3)S_(4).Further analysis shows that the order of contribution to magnetism is d orbital>s orbital>p orbital,and the magnetism of cluster Mo_(3)S_(4)is mainly contributed by the spin-up electrons of Mo-4d orbital.