Departament de Química Física and Institut de Química Teòrica i Computacional, Universitat de Barcelona, E-08028 Barcelona, Spain.
Phys Chem Chem Phys. 2010 Aug 14;12(30):8505-12. doi: 10.1039/c004375c. Epub 2010 Jun 21.
Using a variety of computational approaches, we demonstrate that the energy landscape of low-density silicon (e.g. silicon clathrates) is considerably more complicated than suggested by previous studies and identify several new prospective low-energy silicon allotropes. Many of our new prospective silicon allotropes contain 4-membered rings, previously thought to be incompatible with low-energy structures, while all of them have surprisingly large unit cells. These allotropes are found by identifying minima on the energy landscape of silicon, as described by the Tersoff potential, in two distinctly different ways: (i) via a random search approach and (ii) by optimising sets of four-coordinated nets previously enumerated for silica. The lowest-energy minima found are subsequently refined using periodic density functional theory. We discuss the merits of both approaches and identify the need for robust global optimisation methods that can efficiently explore low-symmetry systems with large numbers of atoms.
利用多种计算方法，我们证明了低密度硅（例如硅笼合物）的能量景观比之前的研究所表明的要复杂得多，并确定了几种新的潜在低能量硅同素异形体。我们的许多新的潜在硅同素异形体都含有 4 元环，以前认为这与低能量结构不兼容，而它们所有的结构都有令人惊讶的大单元。这些同素异形体是通过两种截然不同的方式来确定硅的能量景观上的最小值来找到的：（i）通过随机搜索方法，和（ii）通过优化以前为二氧化硅枚举的四配位网的集合。随后使用周期性密度泛函理论对发现的最低能量最小值进行了细化。我们讨论了这两种方法的优点，并确定了需要稳健的全局优化方法，以便有效地探索具有大量原子的低对称系统。
