Pham Hung Tan, Majumdar Devashis, Leszczynski Jerzy, Nguyen Minh Tho
Computational Chemistry Research Group, Ton Duc Thang University, Ho Chi Minh City, Vietnam.
Interdisciplinary Center for Nanotoxicity, Department of Chemistry and Biochemistry, Jackson State University, Jackson, Mississippi 39217, USA.
Phys Chem Chem Phys. 2017 Jan 25;19(4):3115-3124. doi: 10.1039/c6cp05964c.
Geometries and electronic properties related to the ground state stabilities of several SiM clusters (M: second-row (Nb and Mo) and third-row (Ta and W) transition metals, and their mixed bimetallic clusters M: NbMo and TaW) were explored using density functional theory (DFT) computations. The computed results show that two different structural motifs emerge as the global energy minima of such clusters. They are basically singlet tubular structures in either a C prism (A) or a C antiprism (A) form. Other structural shapes are also possible for higher-energy isomers and in higher spin states. 58-valence electron systems including NbSi, TaSi, MoSi, WSi, NbMoSi and TaWSi are thermodynamically stable as C prism global minima on the corresponding potential energy surfaces. Clusters containing 60 valence electrons include MoSi, WSi, NbSi, TaSi, NbMoSi and TaWSi and they prefer a C anti-prism form. In the mixed MoNbSi and TaWSi open-shell systems, both resulting C (A) and C (A) forms are nearly degenerate. The formation of SiM clusters in such specific ground state symmetry is explained using the Jellium model and orbital interaction analyses. The investigations lead further to a proposal for a simple model of a bimetallic configuration using the nature of interactions of the transition metal d-d dimeric bond with the Si host, to interpret the formation of such MSi clusters.
利用密度泛函理论（DFT）计算，探索了与几种硅化物团簇（M：第二周期（铌和钼）和第三周期（钽和钨）过渡金属，以及它们的双金属混合团簇M：铌钼和钽钨）基态稳定性相关的几何结构和电子性质。计算结果表明，两种不同的结构基序作为此类团簇的全局能量最小值出现。它们基本上是单重态管状结构，呈C棱柱（A）或C反棱柱（A）形式。对于能量较高的异构体和较高自旋态，也可能存在其他结构形状。包括NbSi、TaSi、MoSi、WSi、NbMoSi和TaWSi在内的58价电子体系在相应势能面上作为C棱柱全局最小值是热力学稳定的。含有60个价电子的团簇包括MoSi、WSi、NbSi、TaSi、NbMoSi和TaWSi，它们更倾向于C反棱柱形式。在混合的MoNbSi和TaWSi开壳层体系中，产生的C（A）和C（A）形式几乎是简并的。利用凝胶模型和轨道相互作用分析解释了这种特定基态对称性下硅化物团簇的形成。这些研究进一步提出了一个简单的双金属构型模型，利用过渡金属d-d二聚体键与硅主体的相互作用性质来解释此类MSi团簇的形成。
