CheckCIF-DENSX01

PROC-NAME: DENSX01 Type_1

PURPOSE: To check that the _exptl_crystal_density_meas matches the _exptl_crystal_density_diffrn.

PROCEDURE:

CALCULATE

RD = _exptl_crystal_density_diffrn / _exptl_crystal_density_meas

TEST

IF RD is 0.80 < > 1.20 issue ALERT A

         "Alert A The ratio of the calculated to measured crystal density lies outside the range 0.80 < > 1.20"

RD is 0.90 < > 1.10 issue ALERT B

         "Alert B The ratio of the calculated to measured crystal density lies outside the range 0.90 < > 1.10"

RD is 0.95 < > 1.05 issue ALERT C

         "Alert C The ratio of the calculated to measured crystal density lies outside the range 0.95 < > 1.05"

        The calculated density given in the CIF differs significantly from the experimentally measured density quoted in the CIF. Check that you have measured, calculated and entered the densities correctly and that in your calculations you have allowed correctly for all distinct moieties present, including any solvent and all H atoms, and not the contents implied by the model if there are differences due to the omission of a few H atoms or solvent atoms.

(http://journals.iucr.org/services/cif/checking/DENSX_01.html)

目的：检查_exptl_crystal_density_meas是否与_exptl_crystal_density_diffrn相匹配。

过程：

计算

RD = _exptl_crystal_density_diffrn / _exptl_crystal_density_meas

检查

若RD小于0.80或者大于1.20，则发布A级警告

         "Alert A The ratio of the calculated to measured crystal density lies outside the range 0.80 < > 1.20"

若RD小于0.90或者大于1.10，则发布B级警告

         "Alert B The ratio of the calculated to measured crystal density lies outside the range 0.90 < > 1.10"

若RD小于0.95或者大于1.05，则发布C级警告

         "Alert C The ratio of the calculated to measured crystal density lies outside the range 0.95 < > 1.05"

        CIF中给出的密度计算值与CIF中引用的密度实验测量值显著不同。检查是否已正确测量，计算和输入密度值，并且再计算中是否正确允许所存在的所有不同部分，包括任何溶剂和所有氢原子，若由于删除了一些氢原子或溶剂原子而存在差异，则不应与模型所暗示的内容相对应。

例：DENSX01_ALERT_1_A The ratio of the calculated to measured crystal density lies outside the range 0.80 <> 1.20

Calculated density = 1.753

Measured density = 0.000

警告原因：晶体密度的计算值与测试值的比值超出限定范围。

解决策略：将CIF中“_exptl_crystal_density_meas”后的“0”改为“?”。