Convergence Properties of Crystal Structure Prediction by Quasi-Random Sampling.
Convergence Properties of Crystal Structure Prediction by Quasi-Random Sampling.
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DOI：
10.1021/acs.jctc.5b01112
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发表时间：
2016-02-09
影响因子：
5.5
通讯作者：
Day GM
中科院分区：
文献类型：
--
作者：
Case DH;Campbell JE;Bygrave PJ;Day GM
在从头计算晶体结构预测（CSP）的过程中，产生一组对晶体堆积可能性的构型空间进行采样的试验结构是一个必不可少的步骤。一个有效的方法来执行这样的搜索依赖于低差异，准随机抽样，和我们的实现这样的搜索分子晶体在本文中描述。在这里，我们限制自己的刚性有机分子，并考虑其几何性质，建立审判晶体包装为起点，局部晶格能最小化。我们还描述了一种方法来匹配相同结构的实例，我们用它来衡量我们的包装搜索的收敛走向完整性。这些工具的使用被证明为一组具有不同分子特性的分子，并作为CSP已被应用的应用领域的代表。一个重要的发现是，最低能量的晶体结构通常位于早期和频繁在相空间的准随机搜索。通常是对更高能量结构的完整采样需要扩展采样。我们展示了如何首先可以改进该过程，通过针对所生成的晶体结构的体积，然后扩展到一系列空间群，以进行完整的CSP搜索，并定位实验观察到的假设多晶型物和列表。由于所描述的方法也被创建为基于CSP的更复杂的方法，这些方法正在Global Lattice Energy Explorer（Glee）软件中开发，因此简要讨论了其中的一些扩展。
Generating sets of trial structures that sample the configurational space of crystal packing possibilities is an essential step in the process of ab initio crystal structure prediction (CSP). One effective methodology for performing such a search relies on low-discrepancy, quasi-random sampling, and our implementation of such a search for molecular crystals is described in this paper. Herein we restrict ourselves to rigid organic molecules and, by considering their geometric properties, build trial crystal packings as starting points for local lattice energy minimization. We also describe a method to match instances of the same structure, which we use to measure the convergence of our packing search toward completeness. The use of these tools is demonstrated for a set of molecules with diverse molecular characteristics and as representative of areas of application where CSP has been applied. An important finding is that the lowest energy crystal structures are typically located early and frequently during a quasi-random search of phase space. It is usually the complete sampling of higher energy structures that requires extended sampling. We show how the procedure can first be refined, through targetting the volume of the generated crystal structures, and then extended across a range of space groups to make a full CSP search and locate experimentally observed and lists of hypothetical polymorphs. As the described method has also been created to lie at the base of more involved approaches to CSP, which are being developed within the Global Lattice Energy Explorer (Glee) software, a few of these extensions are briefly discussed.