X-ray diffraction data-assisted structure searches
X-ray diffraction data-assisted structure searches
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X 射线衍射数据辅助结构搜索
DOI：
10.1016/j.cpc.2016.11.007
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发表时间：
2017
影响因子：
6.3
通讯作者：
Ma Yanming
中科院分区：
文献类型：
--
作者：
Gao Pengyue;Tong Qunchao;Lv Jian;Wang Yanchao;Ma Yanming
X射线衍射法是一种重要的结构测定技术。然而，在传统的方法中，需要估计的结构信息(如晶胞参数和空间群)才能从X射线衍射数据中确定精确的结构。我们提出了一种通用的全局搜索方法，可以从实验粉末的X射线衍射数据中确定晶体结构，而不需要猜测结构信息。与传统的以总能量作为适应度函数的结构预测方法不同，该方法的适应度是模拟的X射线衍射谱与实验的X射线衍射谱之间的差异程度。为了提高利用粉末X射线衍射仪进行结构搜索的效率，实现了背景减除、模拟退火法优化轮廓参数、利用Calypso进行结构演化等技术。通过对已知结构(六方氧化锌和锐钛矿型二氧化钛)的预测，证明了该方法的有效性和稳健性。用该方法对CaLi2和Ca3C2的高压相进行了研究，发现了候选结构(C2221为CaLi2，Cm2为Ca3C2，12.5 GPa时为Cm2m)，其模拟的X射线衍射图与实验相吻合。
X-ray diffraction (XRD) is an important technique for structure determination. However, in traditional methods, estimated structural information (eg, unit cell parameters and space group) is required to determine the precise structure from XRD data. We propose a versatile global search method for determining crystal structures from experimental powder XRD data without guessed structural information. Unlike in traditional structure prediction, which uses total energy as the fitness function, the fitness in our method is the degree of dissimilarity between the simulated and the experimental XRD patterns. To improve the efficiency of structure searching using powder XRD data, several techniques are implemented, including background subtraction, profile parameter optimization by simulated annealing, and structure evolution using CALYPSO. The efficiency and robustness of our method is demonstrated here using predictions of previous known structures (hexagonal ZnO and anatase TiO 2). The method is also used to explore the high-pressure phases of binary compounds CaLi 2 and Ca 3 C 2; it uncovers candidate structures (C 222 1 for CaLi 2 at 54 GPa and C m 2 m for Ca 3 C 2 at 12.5 GPa) whose simulated XRD patterns agree with their experimental patterns.