PLAT931 Type_5 Test for Missed Twinning from FCF/CIF data

Check the proposed Twin Law. The entry in () represents the proposed rotation axis in reciprocal space and the one in [] the corresponding rotation is direct space. The relevant Twin Matrix can be found in the file '.ckf'.

Note: This test is based on F(calc) values calculated with the data in the CIF. This ALERT can be ignored when twinning has been addressed in the refinement (As indicated by the Absence of ALERT 930). Please check whether twinning is mentioned in the write-up of the paper.

(http://journals.iucr.org/services/cif/checking/PLAT931.html)

例：PLAT931_ALERT_5_G Found Twin Law ( 0 1 1)[ ??] Estimated BASF

警告原因：可能有孿晶存在。

解決策略：加入欒晶法則按孿晶精修，如果不行需重新還原數(shù)據(jù)并拆分。

PLAT933 Type_2 Report number of OMIT records in embedded .res

This ALERT reports on the number of OMIT records (Reflections omitted from the least-squares refinement) in the CIF.

(http://journals.iucr.org/services/cif/checking/PLAT933.html)

例：PLAT933_ALERT_2_B Number of OMIT Records in Embedded .res File ...????????? 4 Note

警告原因：使用了OMIT命令。

解決策略：無需解決，有合理解釋即可。

PLAT934 Type_3 Report number of outliers

This ALERT reports on the number of reflections for which I(obs) and I(calc) differ more that 10 times SigmaW. (The latter being the square root of 1.0/weight for that reflection in the L.S. refinement). The reason for those deviations should be investigated. When shown to be systematic errors, those reflections are best removed from the refinement and their omission from the refinement reported in the experimental section of an associated paper.

(http://journals.iucr.org/services/cif/checking/PLAT934.html)

例：PLAT934_ALERT_3_B Number of (Iobs-Icalc)/SigmaW > 10 Outliers .... 2 Check

警告原因：有些高角度衍射點擬合誤差較大(需上傳fcf文件)。

解決策略：檢查精修模型是否有問題，如果模型沒有錯可以O(shè)MIT掉這些點并在文章實驗部分說明。

PLAT935 Type_2 Pseudo Extinction Parameter Test

Both significantly positive and significantly negative values should invoke a search for a likely cause and a corrective action.

(http://journals.iucr.org/services/cif/checking/PLAT935.html)

警告原因：存在偽消光參數(shù)。

解決策略：給出合理解釋。

PLAT936 Type_2 Test for DAMP instruction in embedded .res

The reason for the use of a DAMP instruction in the final refinement job should be discussed/reported. 'DAMP 0.0' should not be used for small molecule refinement since it masks non-convergence.

(http://journals.iucr.org/services/cif/checking/PLAT936.html)

警告原因：精修中使用了DAMP命令。

解決策略：刪除該命令，或者有合理解釋即可。

PLAT937 Type_4 Report Exponential Term in SHELXL weight expression

The use of an exponential term in the SHELXL weight expression is not recommended in the final refinement stage (i.e. the third parameter in the SHELXL WGHT record).

(http://journals.iucr.org/services/cif/checking/PLAT937.html)

警告原因：在最終精修中使用了權(quán)重的指數(shù)項。

解決策略：刪除WGHT中第三個參數(shù)后，重新精修生成CIF文件。

PLAT939 Type_3 Test for high not weight optimized S value

SHELXL optimizes two weight parameters to bring the S value close to 1.0. This ALERT reports the S value based on the supplied sigma(I) only. A large value of the last generally indicates the presence of large outliers in the data set. Examples are reflections 'measured' behind the beam stop. (See also ALERT_919). The latter are best left out with an OMIT instruction.

(http://journals.iucr.org/services/cif/checking/PLAT939.html)

例：PLAT939_ALERT_3_A Large Value of Not (SHELXL) Weight Optimized S . 738.33

警告原因：同PLAT083類似，權(quán)重值較大。

解決策略：OMIT掉誤差較大的點，檢查精修結(jié)構(gòu)是否有問題，按照欒晶精修，或者升空間群。

PLAT940 Type_3 Test for wR2 refinement with all data

Apparently, observed data with I > n * sigma(I) were used in the F**2 least squares refinement, rather than all observed data.

(http://journals.iucr.org/services/cif/checking/PLAT940.html)

例：PLAT940_ALERT_3_A F**2 Refinement with I .GT. n * Sigma(I) only ..?

警告原因：可能是_reflns_threshold_expression項缺失。

解決策略：_reflns_number_total和_reflns_number_gt應(yīng)相差較大，total指的是全部可觀察衍射點，而 gt 通常是指>2\s(I)的衍射。即使是P-1空間群，這二個值的差也要在一倍以上。除非你的單晶是合金，且有極高對稱性的。到原始數(shù)據(jù)中去尋找原因。

PLAT941 Type_3 Test fit Low Measured hkl Multiplicity

Multiple hkl measurements are advised, either of symmetry related reflections and/or at differen psi angle values around the diffrection vector normal to the diffracting PLAne. A good multiplicity is needed for a meaningful multi-scan based correction for absorption. Details can be found in the ckf file.

(http://journals.iucr.org/services/cif/checking/PLAT941.html)

例：PLAT941_ALERT_3_G Average HKL Measurement Multiplicity ........... 2.7 Low?

警告原因：hkl多重性較低。

解決策略：可能需要重新收集數(shù)據(jù)。否則需要給出合理解釋。

PLAT949 Type_5 Test for Poisson type Intensity Sigma Distribution

Check the validity of the observed reflection data.

(http://journals.iucr.org/services/cif/checking/PLAT949.html)

警告原因：可觀測衍射數(shù)據(jù)無效。

解決策略：可能需要重新收集數(shù)據(jù)。否則需要給出合理解釋。