Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.
Nanoscale. 2018 Mar 15;10(11):5124-5132. doi: 10.1039/c7nr09440j.
Calculations of low free energy structures of gold clusters with a few hundred to a few thousand atoms have been performed. For the study to be computationally feasible, a systematic scheme for generating low energy atomic structures with a given structural motif and a chosen size is used. Comparison of the relative stability of clusters with the decahedral and FCC motifs reveals periodic windows of stability for asymmetric, open-shell FCC clusters while the stability of the decahedral structural motif shows a smoother variation in stability with cluster size. As a result, the FCC structural motif is most stable for clusters with around 440, 610, 800, 1050… atoms, while the decahedral motif is more stable for atomic numbers of around 525, 705, 925, 1175… These new 'magic numbers' represent regions around which a number of asymmetric, open shell clusters of a given motif are most stable, in contrast to the discrete set of highly symmetric magic size structures that are commonly cited. As temperature is raised, the decahedral motif gains stability over the FCC motif. These results help explain reported experimental observations and can guide future laboratory preparations of shape selected clusters.
已经对具有几百到几千个原子的金团簇的低自由能结构进行了计算。为了使研究在计算上可行，使用了一种系统的方案来生成具有给定结构模式和所选尺寸的低能量原子结构。比较具有十面体和 FCC 图案的团簇的相对稳定性揭示了非对称、开壳 FCC 团簇的稳定周期性窗口，而十面体结构图案的稳定性随着团簇尺寸的变化显示出更平滑的稳定性变化。因此，FCC 结构图案对于大约 440、610、800、1050……个原子的团簇最稳定，而对于大约 525、705、925、1175……个原子的团簇，十面体图案更稳定。这些新的“魔术数字”代表了给定图案的许多非对称、开壳团簇最稳定的区域，与通常引用的离散的高度对称的魔术尺寸结构集形成对比。随着温度的升高，十面体图案相对于 FCC 图案获得了稳定性。这些结果有助于解释报道的实验观察结果，并可以指导未来对形状选择的团簇的实验室制备。
