CheckCIF-PLAT081-090
PLAT081 Type_1 - NoMaximum Shift/Error Given
A maximum shift/error should be specified in order to judge convergence.
(http://journals.iucr.org/services/cif/checking/PLAT081.html)
警告原因：未在CIF中给出偏移值。
解决策略：一般为误删除，重新精修生成CIF即可。
PLAT082 Type_2 Test for reasonable R1
A higher than usual R1 indicates either an insufficient model or poor quality data.
(http://journals.iucr.org/services/cif/checking/PLAT082.html)
警告原因：R1值较大。
解决策略：检查是否已经精修权重，再检查模型是否正确，最后检查数据质量是否足够高。
PLAT083 Type_2 Test for extreme second weighting parameter (SHELXL)
The second parameter on the SHELXL weighting line has an exceptionally large value. This may indicate either improper reflection s.u.s or an unresolved problem such as missed twinning.
(http://journals.iucr.org/services/cif/checking/PLAT083.html)
警告原因：权重因子中第二个数值较大，可能由于某些点拟合误差较大或者孪晶。
解决策略：OMIT掉误差较大的点或者按孪晶精修。
PLAT084 Type_3 Test for reasonable wR2
wR2 will in general have a value twice of that of R1 with refinement on F**2. Significantly larger values usually indicate a poor refinement model. Also check for unaccounted for twinning.
(http://journals.iucr.org/services/cif/checking/PLAT084.html)
警告原因：wR2值较大，一般来说wR2值约是R1值的两倍。
解决策略：检查是否已经精修权重，再检查模型是否正确，最后检查数据质量是否足够高或是否孪晶。
PLAT085 Type_2 Test for default SHELXL weighting scheme
The weighting scheme is found to be left at the SHELXL default. This default is recommended for the preliminary structure refinement. It is uncommon that this unoptimized weight gives the best final refinement result.
(http://journals.iucr.org/services/cif/checking/PLAT085.html)
警告原因：在最后结果中，权重的系数为SHELXL给出的默认值，未进行精修。
解决策略：精修权重即可。
PLAT086 Type_2 Test for reasonable S (Too Low)
S should in general be close to 1 at the end of a refinement with a proper weighting scheme. If not, there might be significant unresolved problems with the model.
(http://journals.iucr.org/services/cif/checking/PLAT086.html)
警告原因：权重值为远小于1。
解决策略：检查是否已经精修权重，再检查模型是否正确，最后检查数据质量是否足够高或是否孪晶。
PLAT087 Type_2 Test for reasonable S (Too High)
S should in general be close to 1 at the end of a refinement with a proper weighting scheme. If not, there might be significant unresolved problems with the model.
(http://journals.iucr.org/services/cif/checking/PLAT087.html)
警告原因：权重值为远大于1。S值较大
解决策略：检查是否已经精修权重，再检查模型是否正确，最后检查数据质量是否足够高。
PLAT088 Type_3 Test for reasonable Data / parameter ratio (centro)
The data/parameter ratio should in general be higher than 10 for a quality structure determination. This ratio can be improved by not refining C-H parameters other than riding on their carrier atom.
(http://journals.iucr.org/services/cif/checking/PLAT088.html)
警告原因：对于中心对称结构，数据参数比最好大于10。
解决策略：可以采用骑式模型减少参数个数，无法解决只能重新还原或者收集数据。
PLAT089 Type_3 Test for reasonable Data / parameter ratio (non-centro) (Zmax < 18)
The data/parameter ratio should in general be higher than 7 for a quality determination of a structure containing atoms with Z less than 18. This ratio can be improved by not refining C-H parameters other than riding on their carrier atom.
Note: The number of reflections used in this ratio is the number obtained by Laue group averaging.
(http://journals.iucr.org/services/cif/checking/PLAT089.html)
警告原因：对于非中心对称结构，且晶胞内分子数小于18，数据参数比最好大于7。
解决策略：可以采用骑式模型减少参数个数，无法解决只能重新还原或者收集数据。
PLAT090 Type_3 Test for reasonable Data / parameter ratio (non-centro) (ZMAX > 18)
The data/parameter ratio should in general be higher than 8 for a quality determination for a structure containing heavy atoms with ZMAX greater than 17. This ratio can be improved by not refining C-H parameters other than riding on their carrier atom.
(http://journals.iucr.org/services/cif/checking/PLAT090.html)
警告原因：对于非中心对称结构，且晶胞内分子数小于18，数据参数比最好大于8。
解决策略：可以采用骑式模型减少参数个数，无法解决只能重新还原或者收集数据。删除omit或者shel命令重新精修。
例：Alert level B
Crystal system given = trigonal
PLAT090_ALERT_3_B Poor Data / Parameter Ratio (Zmax > 18) ........ 5.15 Note
解决策略：数据收的不够导致了强点参数比低于最低要求7，所以才会出现这个错误，要解决的话只能重新收数据了，再收的时候不要按照空间群收了，要收四分之一球或二分之一球。
