CheckCIF-DIFMX02

PROC-NAME: DIFMX02 Type_1

PURPOSE: To check that if _refine_diff_density_max is not within expected limits that the adjacent site is identified.

PROCEDURE:

DMAX = _refine_diff_density_max

DTEST = 0.1 * ZMAX

TEST

IF DMAX > DTEST*.75 atom site should be identified.

Issue ALERT C

         "Alert C The minimum difference density is > 0.1*ZMAX*0.75 The relevant atom site should be identified."

        The maximum residual electron density is larger than normally expected. Please specify the name of the nearest atom to this maximum and its distance from the maximum.

(http://journals.iucr.org/services/cif/checking/DIFMX_02.html)

目的：检查_refine_diff_density_max是否不在确定相邻位置的预期范围内。

过程：

DMAX = _refine_diff_density_max

DTEST = 0.1 * ZMAX

检查

若DMAX > DTEST*.75原子位置应被识别

则发布C级警告

         "Alert C The minimum difference density is > 0.1*ZMAX*0.75 The relevant atom site should be identified."

        最小残余电子密度值比预期更负。请指定最接近此最小残余电子密度峰的原子名称及它们之间的距离。

警告原因：最小残余电子密度值超出预期范围。

解决策略：C级警告一般可以不处理。若确定没有其他问题，则指定最接近此最小残余电子密度峰的原子名称及它们之间的距离。

关于该警告的一个具体解释例子参考下面链接中的公众号文章： https://mp.weixin.qq.com/s/irYbkyXuk1kRluJryBZYeg