FN - CRITERION FOR RATING POWDER DIFFRACTION PATTERNS AND EVALUATING THE RELIABILITY OF POWDER-PATTERN INDEXING
FN - CRITERION FOR RATING POWDER DIFFRACTION PATTERNS AND EVALUATING THE RELIABILITY OF POWDER-PATTERN INDEXING
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DOI：
10.1107/s002188987901178x
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发表时间：
1979-01-01
影响因子：
6.1
通讯作者：
SNYDER, RL
中科院分区：
文献类型：
--
作者：
SMITH, GS;SNYDER, RL
目前已有30 000多个粉末衍射图可供参考。建议对存档的模式以及提交出版的新模式分配定量质量因素。一个简单易用的品质因数FN，涵盖了衍射线位置测量的准确性和图案的完整性，已经推导出：FN =（1/2）。|{\bar \Delta 2 \θ}|）（N/Nposs），其中Nposs是可能达到第N条观察线的独立衍射线的数量，|{\bar \Delta 2 \θ}|是观察到的2 θ值和计算出的2θ值之间的平均绝对差异。该品质因数提供了粉末图案的快速评估，与R因子提供单晶结构测定的评级大致相同。该品质因数还提供了一种评估仅从粉末数据得出的装置的可靠性的手段。目前FN的排名计划被证明是上级德沃尔夫的M20的排名模式。建议为此目的停止使用后者。给出了粉末衍射图FN等级的使用和实施指南。
At present, over 30 000 powder diffraction patterns are available as references. It is proposed that the patterns on file as well as new patterns submitted for publication be assigned quantitative quality factors. A simple-to-use figure of merit, FN, covering both accuracy in the measurement of the positions of the diffraction lines and completeness of the pattern, has been derived: FN = (1/|{\bar \Delta 2 \theta}|) (N/Nposs), where Nposs is the number of independent diffraction lines possible up to the Nth observed line and |{\bar \Delta 2 \theta}| is the average absolute discrepancy between observed and calculated 2θ values. This figure of merit provides a rapid evaluation of powder patterns, in much the same way as the R factor provides a rating for single-crystal structure determinations. This figure of merit also provides a means to assess the reliability of a unit derived solely from powder data. At present FN ranking scheme is shown to be superior to de Wolff's M20 for ranking patterns. It is recommended that use of the latter be discontinued for that purpose. Guidelines are given on the use and implementation of the FN rating of powder diffraction patterns.