PROC-NAME: RFACG01 Type_3

PURPOSE: To check that _refine_ls_R_factor_gt is within expected limits.

PROCEDURE:

TEST

IF _refine_ls_R_factor_gt > 0.20 issue ALERT A

?? "Alert A The value of the R factor is > 0.20"

> 0.15 issue ALERT B

?? "Alert B The value of the R factor is > 0.15"

> 0.10 issue ALERT C

?? "Alert C The value of the R factor is > 0.10"

The value of _refine_ls_R_factor_gt is equivalent to the conventional R-factor and when calculated using a threshold of 2sigma(I) in _reflns_threshold_expression, values less than 0.07 are normally expected. Higher values should be accompanied by a suitable explanation in the _publ_section_exptl_refinement section. However, authors should first ensure that there are not overlooked problems associated with the data or the model. Elevated values for _refine_ls_R_factor_gt may be indicative of a need to recollect the data from a crystal of higher quality or to improve or correct the model. Consider the following:

(a) The absorption corrections are inadequate or inappropriate.

(b) The overall quality of the data may be poor due to the crystal quality.

(c) There is untreated twinning either in the form of unconsidered merohedral twinning or where overlap from the second twin domain in non-merohedral twins (which may have been ignored in the data collection) causes errors in the intensities of some reflections.

(d) The model is incorrect or incomplete in terms of incorrect element assignment, missing atoms or unmodelled or inadequately modelled disorder or solvent atoms.

IF _refine_ls_R_factor_obs has been used issue General ALERT

?? "_refine_ls_R_factor_obs is an old dataname which has been superceded by _refine_ls_R_factor_gt"

You are using an "old-fashioned", but still legal data name: _refine_ls_R_factor_obs. Please update the item to match the currently preferred name of _refine_ls_R_factor_gt. To ease this problem for the future, it is recommended that you upgrade or modify your CIF generating software accordingly.

IF neither _refine_ls_R_factor_gt or _refine_ls_R_factor_obs are present issue Gerneral ALERT

?? "Alert C Test not performed. _refine_ls_R_factor_gt is not present."

It is compulsory to report the conventional R-factor under the item _refine_ls_R_factor_gt. This data name is not present in your CIF or has not been assigned a value. Please insert the data item with an apropriate value.

(http://journals.iucr.org/services/cif/checking/RFACG_01.html)

例：RFACG01_ALERT_3_B The value of the R factor is > 0.10

?? ?????????R factor given? 0.129

警告原因：R因子不在預期范圍內。

解決策略：給出合理解釋即可。