CheckCIF-PLAT900-910

plaT900 Type_1 Test for 'No-matching reflection file'

Likely cause: Dataset names in the CIF and FCF differ.

Note: FCF Validation is Skipped for this Entry.

(http://journals.iucr.org/services/cif/checking/plaT900.html)

警告原因：无衍射文件。

解决策略：用SHELXL 2014及以上版本精修即可。

plaT901 Type_1 Test for CIF & FCF CELL Not Matching

Possible causes: wrong dataset, CIF or FCF parameters edited inconsistently or cell parameters for transformed cell (e.g. P21/n <-> P21/c).

Note: FCF Validation is Skipped for this Entry.

(http://journals.iucr.org/services/cif/checking/plaT901.html)

警告原因：CIF和FCF中晶胞不匹配。

解决策略：一般不会出现，有合理解释即可。

plaT902 Type_1 Test for non-zero number of recognised reflections in FCF

Either no reflections are found in the FCF or the FCF is uninterpretable due to unknown format or editing.

Note: FCF Validation is Skipped for this Entry.

(http://journals.iucr.org/services/cif/checking/plaT902.html)

例：plaT902_ALERT_1_A No (Interpretable) Reflections found in FCF .... Please Check

警告原因：FCF中未发现可解释的衍射点。

解决策略：一般不会出现，有合理解释即可。

plaT903 Type_1 Test for Fobs=Fcalc in FCF

Check the FCF file for F(obs) equal F(calc) [of F(obs)**2 equal F(calc)**2].

(http://journals.iucr.org/services/cif/checking/plaT903.html)

警告原因：FCF中Fobs=Fcalc。

解决策略：一般不会出现，有合理解释即可。

plaT904 Type_1 Test for NREF .GT. NPAR in the CIF

The number of reflections found in the reflection file is less than the number of parameters reported in the CIF.

(http://journals.iucr.org/services/cif/checking/plaT904.html)

警告原因：衍射文件(hkl文件)中衍射点数目少于CIF中报告的参数数目。

解决策略：一般不会出现，有合理解释即可。

plaT905 Type_3 Report Negative K values in the Analysis of Variance

Scale Factors (i.e. K = Mean[Fo**2] / Mean [Fc**2]) for selected groups of reflections, as listed in the Analysis of Variance Section #7 of the FCF validation report, are expected to have a value of about 1.000. Strong deviations should be investigated, acted upon or explained. (see also SHELXL manual). A reason can be meaningless (weak) high order data where a cut-back of the resolution might be indicated. Incorrect background treatment can lead to numerous negative observed intensities for weak reflections (i.e. F(calc) close to zero. For details see the Analysis-of-Variance Section in the '.ckf' file.

(http://journals.iucr.org/services/cif/checking/plaT905.html)

例：plaT905_ALERT_3_C Negative K value in the Analysis of Variance ...

警告原因：K值(标度因子，K = Mean[Fo**2] / Mean [Fc**2])为负。

解决策略：使用Shel 999 0.84删除高角度的点，如无法解决有合理解释即可。

plaT906 Type_3 Report Large K values in the Analysis of Variance

Scale Factors (i.e. K = Mean[Fo**2] / Mean [Fc**2]) for selected groups of reflections, as listed in the Analysis of Variance Section #7 of the FCF validation report, are expected to have a value of about 1.000. Strong deviations should be investigated, acted upon or explained. (see also SHELX manual). For details see the Analysis-of-Variance Section in the '.ckf' file.

(http://journals.iucr.org/services/cif/checking/plaT906.html)

例：plaT906_ALERT_3_C Large K value in the Analysis of Variance ...... 12.734 Check

警告原因：K值(标度因子，K = Mean[Fo**2] / Mean [Fc**2])偏差较大。

解决策略：使用Shel 999 0.84删除高角度的点，如无法解决有合理解释即可。

plaT907 Type_2 Check whether the structure needs to be inverted

A Flack x value generally indicates that the structure needs to be inverted. Check whether the Flack x value is unreliable due to weak anomalous dispersion signal, systematic errors or weak data and against know absolute structure.

(http://journals.iucr.org/services/cif/checking/plaT907.html)

例：plaT907_ ALERT_2_C Flack x > 0.5, structure needs to be inverted? . 1.02 check

警告原因：Flack系数x大于0.5。

解决策略：对结构进行翻转即可。(Olex2中可通过键入inv -f指令实现构型翻转)

plaT908 Type_2 Report on Max Observed data in any Resolution Shell

A low maximum percentage of reflections with I > 2*s(I) may indicate:

1 - Missed translation symmetry. E.g. all reflections hkl weak for l = 2n +1 

2 - Pseudo-merohedral twinning, index > 1. (e.g. non-spacegroup extinctions).

3 - Very weak observed data.

(http://journals.iucr.org/services/cif/checking/plaT908.html)

警告原因：衍射强度低，晶体小或者衍射能力弱。

解决策略：无需解决，有合理解释即可。

plaT909 Type_3 Report of Observed data at Theta Cutoff

This ALERT Reports on whether there is still a significant level of observed data beyond the Theta cutoff of the Dataset. There should be a good reason for a cutoff below sin(theta)/lambda = 0.6.

(http://journals.iucr.org/services/cif/checking/plaT909.html)

例：plaT909_ALERT_3_G Percentage of Observed Data at Theta(Max) still 53 %

警告原因：可观测衍射点比例在高角度仍然较高。衍射强度低，晶体小或者衍射能力弱。

解决策略：无需解决，有合理解释即可。

plaT910 Type_3 Test for missing reflections below Theta(Min)

Possible causes: Beamstop Theta(min) limit set too high, large unit-cell etc. A possible technical solution on CCD based equipment involves the collection of additional images with the detector at a larger distance from the crystal with the beamstop setting changed accordingly.

Alternatively, a large number of low-order reflections might have been 'Omitted' from the (final) least-squares refinement.

(http://journals.iucr.org/services/cif/checking/plaT910.html)

例：plaT910_ALERT_3_B Missing # of FCF Reflection(s) Below Theta(Min). 11 Note

警告原因：缺少部分衍射点。

解决策略：可不解决，有合理解释即可。也可重新收集数据补齐缺失数据。