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晶体结构解析案例74(残余峰-孪晶) 案例来源：CCDC[1] 2348836, 2426674. Chem. Sci. 2024, 15, 20315‒20327.DOI[2]: 10.1039/d4sc04197f. 案例结构如图1所示（由ChemBioDraw[3]绘制）。 ▲图1 案例结构 ▲图2 解析结果 运行PLATON中的TwinRotMat例程，检测到一个孪晶法则，如图3所示。 ▲图3 PLATON给出的孪晶法则 将该孪晶法则添加到精修中，最大残余峰没有降低多少，但只剩下一个B级警报PLAT094，如图4所示。 ▲图4 添加孪晶法则精修的结果 使用PLATON由上述孪晶法则生成的HKFL5格式文件精修，残余峰降低至3.1，无AB级警报，如图5所示。 ▲图5 PLATON生成的HKLF5格式文件精修结果 如果再使用SHELXL[6]指令OMIT将分辨率从0.78 Å截低至0.84 Å，则残余峰进一步降低至2.8，并且R因子也降低了一些，如图6所示。 ▲图6 分辨率截断结果 回到APEX4[7]中，将背景处理方式由“Use Best Plane Background”改为“Use Recurrence Background”，如图7所示。（参阅推文“晶体日记（八）-寻找“Q”峰背后的原因(1)”。） ▲图7 背景处理方式选择 然后将分辨率截断在0.84 Å重新还原，使用PLATON生成的HKLF5格式文件精修，最终残余峰可降低至1.9，如图8所示。 ▲图8 最终处理结果 相关视频： 单晶结构解析练习501(文献案例-数据还原-孪晶-残余峰)：https://www.bilibili.com/video/BV1EGA9eLEVY 数据下载： 论文PDF文档和CIF文件： 提取码: aj7h 晶体数据： 提取码: 7y6q 参考文献 [1] (a) Allen, F. H.The Cambridge Structural Database: A Quarter of a Million Crystal Structuresand Rising. Acta Cryst. 2002, B58, 380–388. DOI:10.1107/S0108768102003890. (b) Groom, C. R.; Bruno, I. 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