Estimation of anomalous signal in diffraction data
Estimation of anomalous signal in diffraction data
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DOI：
10.1107/s0907444906023481
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发表时间：
2006-08-01
影响因子：
2.2
通讯作者：
Dauter, Zbigniew
中科院分区：
文献类型：
--
作者：
Dauter, Zbigniew
衍射数据中存在的异常信号的数量和分辨极限难以客观判断。虽然有几个标准可用于这一目的，这些指标的有用性各不相同，取决于数据冗余、强度估计的准确性及其不确定性以及晶体中有害散射原子的性质等因素。各种指标给出了异常信号的近似测量，但不能提供解决晶体结构的可靠保证。异常信号的最终判据是成功的结构解。目前的数据采集和定相方法是如此先进，以至于通常可以在几分钟内对反射进行定相并获得初步的电子密度图，而晶体仍然驻留在实验站，如果需要，可以收集进一步的数据。
It is difficult to judge objectively the amount and resolution limit of the anomalous signal present in diffraction data. While several criteria can be used for this purpose, the usefulness of these indicators varies and depends on factors such as the data redundancy, the accuracy of the estimation of intensities and their uncertainties, and the properties of the anomalously scattering atoms in the crystal. Various indicators give an approximate measure of the anomalous signal, but do not provide a reliable guarantee that the crystal structure will be solved. The ultimate criterion of the anomalous signal is a successful structure solution. The current data- acquisition and phasing methods are so advanced that it is often possible to phase reflections and obtain preliminary electron- density maps in a few minutes, while the crystal still resides at the experimental station and further data can be collected if necessary.