Toby B H
Argonne National Laboratory, 9700 S. Cass Avenue, 401/B4192, Lemont, IL 60439, USA.
J Appl Crystallogr. 2024 Feb 1;57(Pt 1):175-180. doi: 10.1107/S1600576723011032.
Rietveld refinements are widely used for many purposes in the physical sciences. Conducting a Rietveld refinement typically requires expert input because correct results may require that parameters be added to the fit in the proper order. This order will depend on the nature of the data and the initial parameter values. A mechanism for computing the next parameter to add to the refinement is shown. The fitting function is evaluated with the current parameter value set and each parameter incremented and decremented by a small offset. This provides the partial derivatives with respect to each parameter, along with information to discriminate meaningful values from numerical computational errors. The implementation of this mechanism in the open-source program is discussed. This new method is discussed as an important step towards the development of automated Rietveld refinement technology.
Rietveld精修法在物理科学中有广泛的用途。进行Rietveld精修通常需要专家的参与，因为正确的结果可能需要按适当的顺序在拟合中添加参数。这个顺序将取决于数据的性质和初始参数值。文中展示了一种计算下一个要添加到精修中的参数的机制。使用当前设置的参数值评估拟合函数，并对每个参数增加和减少一个小的偏移量。这提供了关于每个参数的偏导数，以及从数值计算误差中区分有意义值的信息。文中讨论了在开源程序中这种机制的实现。这种新方法被视为朝着自动化Rietveld精修技术发展迈出的重要一步。
