Practical applications of averages and differences of Friedel opposites
Practical applications of averages and differences of Friedel opposites
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DOI：
10.1107/s010876731004287x
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发表时间：
2011-01-01
期刊：
影响因子：
--
通讯作者：
Watkin, D. J.
中科院分区：
文献类型：
--
作者：
Flack, H. D.;Sadki, M.;Watkin, D. J.
研究了平均强度和差强度在结构分析不同阶段的实际应用。它示出了如何这些值可能是正确的和实际使用的空间组的测定阶段。在最小二乘细化的阶段，它表明，增加不同强度的权重并没有提高他们的拟合模型。给出了计算差分电子密度的系数的正确形式。在结构验证的过程中，它进一步表明，所观察到的和模型的差异强度的图提供了一个客观的方法来评估数据的模型拟合，并揭示强度测量的不一致性。作为进一步的工具，结构测定的验证，使用的平均和差异强度的帕特森函数进行了研究，并证明其明显的优势。
The practical use of the average and difference intensities of Friedel opposites at different stages of structure analysis has been investigated. It is shown how these values may be properly and practically used at the stage of space-group determination. At the stage of least-squares refinement, it is shown that increasing the weight of the difference intensities does not improve their fit to the model. The correct form of the coefficients for a difference electron-density calculation is given. In the process of structure validation, it is further shown that plots of the observed and model difference intensities provide an objective method to evaluate the fit of the data to the model and to reveal insufficiencies in the intensity measurements. As a further tool for the validation of structure determinations, the use of the Patterson functions of the average and difference intensities has been investigated and their clear advantage demonstrated.