PROC-NAME: SHFSU01 Type_2

PURPOSE: To check that _refine_ls_shift/su_max is within expected limits.

PROCEDURE:

TEST

IF |_refine_ls_shift/su_max| > 0.20 issue ALERT A

?? "Alert A The absolute value of parameter shift to su ratio > 0.20"

> 0.10 issue ALERT B

?? "Alert B The absolute value of parameter shift to su ratio > 0.10"

> 0.05 issue ALERT C

?? "Alert C The absolute value of parameter shift to su ratio > 0.05"

An elevated value for the largest parameter shift/s.u. is indicative that proper convergence of the refinement has not yet been achieved. Additional cycles of refinement are usually sufficient to achieve adequate convergence and remove this alert. In disordered or otherwise poorly behaved structures, many additional cycles may be required before a suitable level of convergence has been achieved. Any parameters that remain constantly oscillating should be detailed in the _publ_section_exptl_refinement section. You should also consider whether appropriate restraints might help to stabilise ill-defined and oscillating parameters.

IF _refine_ls_shift/esd_max has been used issue General ALERT

?? "_refine_ls_shift/esd_max is an old dataname which has been superceded by _refine_ls_shift/su_max"

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

IF neither _refine_ls_shift/su_max or _refine_ls_shift/esd_max has been used issue ALERT C

?? "Alert C Test not performed. _refine_ls_shift/su_max is not present."

It is compulsory to report the largest parameter shift/s.u. value in the final refinement cycle under the item _refine_ls_shift/su_max. 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/SHFSU_01.html)

例：SHFSU01_ALERT_2_A The absolute value of parameter shift to su ratio > 0.20

警告原因：精修偏移值較大。

解決策略：增加精修輪數(shù)再精修，如果不行需要檢查結(jié)構(gòu)模型是否有問題，是否存在非正定，末端甲基類似基團是否存在旋轉(zhuǎn)。