PROC-NAME: RFACR01 Type_3

PURPOSE: To check that _refine_ls_wR_factor_ref is within expected limits.

PROCEDURE:

TEST

IF _refine_ls_wR_factor_ref > 0.45 issue ALERT A

?? "Alert A The value of the weighted R factor is > 0.45"

> 0.35 issue ALERT B

?? "Alert B The value of the weighted R factor is > 0.35"

> 0.25 issue ALERT C

? ?"Alert C The value of the weighted R factor is > 0.25"

The value of _refine_ls_wR_factor_ref should normally be considerably less than 0.20. 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_wR_factor_ref 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) The crystal is very weakly diffracting, so that a large proportion of essentially "unobserved" reflections are being used in the refinement. You should consider using a better crystal or a data collection at low temperature and/or, if the compound is organic, using Cu radiation.

(d) 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.

(e) 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_wR_factor_obs has been used issue a General ALERT

?? "_refine_ls_wR_factor_obs is an old dataname which has been superceded by _refine_ls_wR_factor_ref"

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

IF neither _refine_ls_wR_factor_ref or _refine_ls_wR_factor_obs are present issue ALERT C

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

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

(http://journals.iucr.org/services/cif/checking/RFACR_01.html)

RFACR01_ALERT_3_B The value of the weighted R factor is > 0.35

警告原因：wR2值大于0.35

解決策略：檢查精修模型是否有改進(jìn)的方面，檢查是否孿晶，檢查數(shù)據(jù)質(zhì)量。