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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Ab initio study of structural stability of Mo-S clusters and size specific stoichiometries of magic clusters
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Ab initio study of structural stability of Mo-S clusters and size specific stoichiometries of magic clusters

机译：从头开始研究Mo-S团簇的结构稳定性和魔术团簇的尺寸比化学计量

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摘要

Using first-principles calculations with ultrasoft pseudopotential formalism and the generalized gradient approximation for the exchange-correlation functional, we study the stability of MonSm (n =1-6 and m ranging from n to 3n) clusters and obtain the optimal stoichiometry for each n corresponding to the magic cluster. It is found that in this size range, the lowest-energy structures favor a core of metal atoms, which is covered by sulfur. In particular, we observe that for Mo6S14 isolated clusters, a 3D structure is significantly lower in energy as compared to platelet structures found recently on Au (111) surface. The composition ratio between S and Mo in the magic clusters is less than 2 for n = 3 and greater than 2 for n < 3. The structural stability of the magic clusters arises from the optimization of the Mo-Mo and Mo- S bonding as well as the symmetry of the cluster. Addition of a terminal sulfur in a magic cluster generally lowers its binding energy. The presence of partially occupied d-orbitals in Mo atoms contributes to Mo-Mo bonding and for higher S concentration it leads to sulfur-sulfur bond formation. The variation in energy due to a change in the sulfur composition suggests that sulfurization of the magic clusters is generally more favorable than desulfurization.
机译：使用具有超软拟势形式的第一性原理计算和交换相关泛函的广义​​梯度近似，我们研究了MonSm（n = 1-6和m范围从n到3n的）簇的稳定性，并获得了每个n的最佳化学计量对应于魔术集群。发现在该尺寸范围内，最低能级的结构有利于被硫覆盖的金属原子核。特别是，我们观察到，对于Mo6S14分离的簇，与最近在Au（111）表面发现的血小板结构相比，3D结构的能量明显较低。当n = 3时，魔术团簇中S和Mo的组成比小于2，而对于n <3，则大于2。魔术团簇的结构稳定性来自于Mo-Mo和Mo-S键的优化以及群集的对称性。在魔术簇中添加末端硫通常会降低其结合能。 Mo原子中部分占据的d轨道的存在有助于Mo-Mo键合，而对于更高的S浓度，它会导致形成硫-硫键。由于硫成分的变化而引起的能量变化表明，魔术团簇的硫化通常比脱硫更有利。

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