Applied Sciences, RMIT University, GPO Box 2476, Victoria, 3001, Australia.
J Phys Chem A. 2010 Mar 18;114(10):3602-8. doi: 10.1021/jp911013t.
In this study we use density functional theory (DFT) to investigate the properties and H adsorption characteristics of structural isomers of the magnesium-doped aluminum cluster, Al(12)Mg. Our results show that the exohedral structure (exo-MgAl(12)) is significantly lower in energy (1.59 eV) than the endohedral structure (endo-Al(12)Mg); however, the exohedral structure shows significant structural distortion. Our calculations demonstrate that H binds favorably to both exohedral and endohedral structures. Generally, binding energies for H to both clusters range from approximately 2.3 to 2.5 eV with atop positions slightly favored, except for addition directly to the exohedral Mg atom, where the binding energy drops to 1.92 eV. We include a DFT molecular dynamics study of the endo-Al(12)Mg and endo-Al(12)MgH clusters which revealed the isomerization to the respective exostructures at finite temperatures (100-600 K). Interestingly, hydrogen adsorption appears to enhance the isomerization.
在这项研究中，我们使用密度泛函理论（DFT）来研究镁掺杂铝团簇 Al(12)Mg 的结构异构体的性质和 H 吸附特性。我们的结果表明，外笼结构（exo-MgAl(12)）的能量明显低于内笼结构（endo-Al(12)Mg）（1.59 eV）；然而，外笼结构表现出显著的结构变形。我们的计算表明，H 有利于与外笼和内笼结构结合。一般来说，H 与两个团簇的结合能约为 2.3 至 2.5 eV，其中 atop 位置略有优势，除了直接添加到外笼的 Mg 原子外，其结合能下降到 1.92 eV。我们包括了对 endo-Al(12)Mg 和 endo-Al(12)MgH 团簇的 DFT 分子动力学研究，该研究揭示了在有限温度（100-600 K）下向相应的外笼结构的异构化。有趣的是，氢吸附似乎增强了异构化。
