plaT850 Type_4 Test for BASF/TWIN Problem in SHELXL

This G_ALERT can be ignored in the case that the so-called 'on-the-cheap' Flack parameter is reported as determined with SHELXL.

Exactly zero values are possible but may also be a software artefact.

The following should be checked:

Problem #1: Some SHELXL97 versions do not allow negative values of the Flack parameter when determined using the BASF/TWIN instructions.

Negative values are set to 0.00001. Refinement may not converge completely.

Problem #2: Some SHELXL97 versions put meaningless values in the CIF for the Flack parameter when 'TWIN -1 0 0 0 -1 0 0 0 -1 2 / BASF' instructions (i.e. an explicit matrix is specified on the TWIN instruction) are used.

Please check the value of BASF (in the list output) against the Flack parameter in the CIF.

(http://journals.iucr.org/services/cif/checking/plaT850.html)

警告原因：結(jié)構(gòu)可能存在孿晶。

解決策略：可用plaTON進(jìn)行孿晶檢測，若有則進(jìn)行孿晶精修。

plaT860 Type_3 Test for restraints used in refinement

The use of restraints used in the refinement should be explained in the write-up of a structure analysis.

It is also recommended to include the refinement instructions in the CIF (e.g. the final .res of a SHELXL refinement) as a comment:

_iucr_refine_instructions_details?

;

TITL

..

(etc.)

;

Note: An exception are restraints for floating origins (e.g. in P21).

(http://journals.iucr.org/services/cif/checking/plaT860.html)

例：plaT860_ALERT_3_G Number of Least-Squares Restraints ............. 660 Note

警告原因：精修中使用了限制。

解決策略：無需解決，限制使用有合理解釋即可。

plaT868 Type_4 Report the Suppression of Olex2/_smtbx_masks use Related ALERTS

ALERTS related to the use of Olex2/_smtbx_masks that can not (yet) be accounted for as part of the VALIDATION algorithms have been suppressed.

(http://journals.iucr.org/services/cif/checking/plaT868.html)

例：plaT868_ALERT_4_G ALERTS Due to the use of _smtbx_masks Suppressed ! Info

警告原因：精修中使用了其他類似squeeze的算法。

解決策略：無需解決，有合理解釋即可。

plaT869 Type_4 Report the Suppression of SQUEEZE use Related ALERTS

ALERTS related to the use of plaTON/SQUEEZE that can not (yet) be accounted for as part of the VALIDATION algorithms have been suppressed.

(http://journals.iucr.org/services/cif/checking/plaT869.html)

例：plaT869_ALERT_4_G ALERTS Related to the use of SQUEEZE Suppressed ! Info

警告原因：精修中使用squeeze扣除了溶劑。

解決策略：無需解決，有合理解釋即可。

plaT870 Type_4 Report the Suppression of some Twinning Related ALERTS

ALERTS related to twinning effects that can not (yet) be accounted for as part of the VALIDATION algorithms have been suppressed.

(http://journals.iucr.org/services/cif/checking/plaT870.html)

例：plaT870_ALERT_4_G ALERTS Related to Twinning Effects Suppressed .. !

警告原因：精修中使用了twin指令進(jìn)行了孿晶精修。

解決策略：無需解決，有合理解釋即可。

plaT871 Type_4 Report the Suppression of some Laue technique related ALERTS

ALERTS related to the use of the Laue technique with a wavelength range have been suppressed.

(http://journals.iucr.org/services/cif/checking/plaT871.html)

警告原因：勞厄技術(shù)相關(guān)的警告被抑制。

解決策略：無需處理，有合理解釋即可。

plaT872 Type_4 Report the Suppression of anharmonic refinement Related ALERTS

ALERTS related to anharmonic refinement have been suppressed. This generally concerns XD and some OLEX2 refinement based CIF's. Internally calculated structure factors are based on the reported harmonic displacement parameters only.

(http://journals.iucr.org/services/cif/checking/plaT872.html)

警告原因：非諧精修相關(guān)的警告被抑制。

解決策略：無需處理，有合理解釋即可。