Structure refinement using precession electron diffraction tomography and dynamical diffraction: theory and implementation
Structure refinement using precession electron diffraction tomography and dynamical diffraction: theory and implementation
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DOI：
10.1107/s2053273315001266
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发表时间：
2015-03-01
影响因子：
1.8
通讯作者：
Correa, Cinthia Antunes
中科院分区：
文献类型：
--
作者：
Palatinus, Lukas;Petricek, Vaclav;Correa, Cinthia Antunes
如果不考虑动态衍射效应，从电子衍射数据中精确地细化结构是不可能的。结构的完整三维模型只能从足够完整的三维数据集获得。在这项工作中，提出了一种方法，从电子衍射断层扫描得到的数据，可能结合进动电子衍射的晶体结构细化。该方法的原理与X射线晶体学中使用的原理相同：围绕旋转轴以一系列小的倾斜步骤收集数据，然后对强度进行积分，并通过最小二乘法对积分强度进行优化。在衍射动力学理论中，反射强度与晶体的取向和厚度以及其他反射的结构因子有着复杂的关系。这种复杂性需要在手术中引入几个特殊参数。该方法在免费提供的晶体学计算系统Jana2006中实现。
Accurate structure refinement from electron-diffraction data is not possible without taking the dynamical-diffraction effects into account. A complete three-dimensional model of the structure can be obtained only from a sufficiently complete three-dimensional data set. In this work a method is presented for crystal structure refinement from the data obtained by electron diffraction tomography, possibly combined with precession electron diffraction. The principle of the method is identical to that used in X-ray crystallography: data are collected in a series of small tilt steps around a rotation axis, then intensities are integrated and the structure is optimized by least-squares refinement against the integrated intensities. In the dynamical theory of diffraction, the reflection intensities exhibit a complicated relationship to the orientation and thickness of the crystal as well as to structure factors of other reflections. This complication requires the introduction of several special parameters in the procedure. The method was implemented in the freely available crystallographic computing system Jana2006.