CheckCIF-ABSMU01
PROC-NAME: ABSMU01 Type_1
PURPOSE: To check that _exptl_absorpt_coefficient_mu value is consistent with the cell contents.
PROCEDURE:
SUMMATION
(1) match _atom_type_symbol with element symbol in table of atomic abs coefficients and extract the AMU value for _diffrn_radiation_type.
IF _diffrn_radiation_type is not Mo, Cu or Ag, issue a General ALERT
"Calculation of _exptl_absorpt_correction_mu not performed for this radiation type."
Only Mo, Cu and Ag radiation is recognized by CHECKCIF for these purposes; wavelengths from other X-ray tubes, synchrotrons or neutrons will cause the calculation of _exptl_absorpt_correction_mu to be skipped.
If you are using Mo, Cu or Ag radiation, but this is not recognised, the format of your keyword entry for _diffrn_radiation_type may be incorrect. The correct format for _diffrn_radiation_type is 'Mo K\a', 'Cu K\a' or 'Ag K\a'.
[Attached are AMU values by Z for CuK\a, MoK\a and AgK\a]
>>> AMU for CuK\a in barn/atom (INT TAB VOL C P193-198)
[.0655, .194, .576, 1.66, 4.15, 8.99, 17.3, 30.4, 49.8, 76.8, 114., 161., 222., 297., 388., 497., 624., 772., 940., 1130., 1350., 1590., 1850., 2130., 2460., 2800., 3140., 476., 547., 629., 719., 819., 929., 1050., 1180., 1320., 1480., 1650., 1830., 2030., 2230., 2460., 2700., 2950., 3230., 3520., 3820., 4150., 4500., 4860., 5250., 5650., 6070., 6520., 7000., 7500., 8030., 8570., 9120., 9680., 10200., 10800., 11000., 10500., 8470., 9770., 3470., 3670., 3930., 4100., 4500., 4600., 4850., 5130., 5720., 5800., 6240., 6340., 6690., 6680., 7540., 7980., 8430., 8810., 8650., 9720., 10200., 10200., 14300., 11800., 10600., 11200.]
>>> AMU for MoK\a in barn/atom (INT TAB VOL C P193-198)
[.0624, .134, .228, .383, .661, 1.15, 1.96, 3.25, 5.15, 7.86, 11.6, 16.5, 22.9, 31., 41., 53.2, 67.8, 85.1, 105., 129., 156., 186., 220., 258., 302., 349., 401., 457., 518., 586., 660., 738., 822., 911., 1000., 1100., 1210., 1320., 1430., 247., 273., 300., 332., 364., 399., 436., 476., 518., 563., 611., 662., 716., 773., 834., 898., 965., 1040., 1110., 1190., 1270., 1350., 1440., 1540., 1630., 1740., 1840., 1950., 2070., 2190., 2310., 2440., 2580., 2720., 2860., 3010., 3160., 3310., 3480., 3650., 3820., 4010., 4190., 4380., 4580., 4070., 3980., 3220., 3300., 5400., 3700., 3870., 4030.]
>>> AMU for AgK\a in barn/atom (INT TAB VOL C P193-198)
[.0614, .128, .206, .313, .479, .745, 1.17, 1.82, 2.77, 4.12, 5.96, 8.42, 11.6, 15.6, 20.6, 26.7, 34.1, 42.9, 53.2, 65.2, 78.9, 94.7, 112., 133., 155., 180., 207., 238., 271., 307., 346., 387., 433., 482., 535., 592., 652., 715., 780., 847., 922., 1150., 1070., 192., 210., 230., 251., 273., 297., 323., 350., 378., 409., 441., 475., 511., 549., 588., 630., 674., 720., 768., 819., 872., 927., 985., 1040., 1110., 1170., 1240., 1310., 1390., 1460., 1540., 1620., 1710., 1800., 1890., 1990., 2090., 2190., 2290., 2400., 2510., 2620., 2730., 2850., 2980., 3110., 3230., 3420., 3500.]
(2) SUM
TOTAMU = AMU * <number of each type in cell>
(3) CALCULATE
MU = 10*TOTAMU/_cell_volume (ie. mu/mm)
RMU = _exptl_absorpt_coefficient_mu/MU
TEST
IF RMU is 0.90 <> 1.10 issue ALERT A
"Alert A The ratio of given/expected absorption coefficient lies outside the range 0.90 <> 1.10"
0.95 <> 1.05 issue ALERT B
"Alert B The ratio of given/expected absorption coefficient lies outside the range 0.95 <> 1.05"
0.99 <> 1.01 issue ALERT C
"Alert C The ratio of given/expected absorption coefficient lies outside the range 0.99 <> 1.01"
This alert does not imply that you need to apply an absorption correction or that your absorption correction is inappropriate in any way. It indicates that your value of the linear absorption coefficient (_exptl_absorpt_correction_mu) in the CIF does not agree with the value calculated from your given unit cell volume and the total number of each element type in the unit cell.
Small differences between your value and the predicted value may arise if your software uses an older (e.g. Int. Tables, Vol. IV, 1974) or a different source of the mass attenuation coefficients. CHECKCIF uses the photon interaction cross sections for the elements given in Int. Tables, Vol. C, 1992, Table 4.2.4.2, pp. 193-198.
Other differences between your value and the predicted value will arise if the unit cell volume, Z or _chemical_formula_sum in your CIF is different from that used to obtain your value of mu. Don't forget that _chemical_formula_sum must correspond with the true sum of all elements in 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.
If multiple moieties such as solvent are present, or one of the moieties possesses or is disordered about a crystallographic symmetry element, ensure that the correct ratio of moieties has been allowed for in the calculation of Z, _chemical_formula_sum and the linear absorption coefficient.
(http://journals.iucr.org/services/cif/checking/ABSMU_01.html)
目的：检查线性吸收系数数值(_exptl_absorpt_coefficient_mu)与晶胞内容的一致性。
(1) 对比原子类型符号(_atom_type_symbol)与原子吸收系数表中的元素符号并提取衍射射线类型(_diffrn_radiation_type)的AMU值。
若衍射射线类型(_diffrn_radiation_type)不是Mo、Cu或Ag，发布一般警告
"Calculation of _exptl_absorpt_correction_mu not performed for this radiation type."
唯有Mo、Cu和Ag射线能够被CHECKCIF识别并用于检查目的；来自其他X射线管、同步加速器或中子的波长将导致跳过线性吸收系数(_exptl_absorpt_correction_mu)的计算。
若使用的射线为Mo、Cu或Ag但未被识别，则可能是衍射射线类型(_diffrn_radiation_type)的关键词条目格式不正确。衍射射线类型(_diffrn_radiation_type)的正确格式为'Mo K\a'、'Cu K\a'或'Ag K\a'。
若RMU小于0.90或大于1.10，发布A类警告
"Alert A The ratio of given/expected absorption coefficient lies outside the range 0.90 <> 1.10"
若RMU小于0.95或大于1.05，发布B类警告
"Alert B The ratio of given/expected absorption coefficient lies outside the range 0.95 <> 1.05"
若RMU小于0.99或大于1.01，发布C类警告
"Alert C The ratio of given/expected absorption coefficient lies outside the range 0.99 <> 1.01"
此警告并非意味着你需要应用吸收校正或者你的吸收校正有任何的不合适。这表明CIF中线性吸收系数值(_exptl_absorpt_correction_mu)与从给定的单胞体积和单胞中每种元素类型的总数计算的值不一致。
若你的软件使用比较早期(例如：Int. Tables, Vol. IV, 1974)或不同来源的质量衰减系数，那么你得到的线性吸收系数值和预测值可能会有微小的差异。CHECKCIF使用的是“Int. Tables, Vol. C, 1992, Table 4.2.4.2, pp. 193-198.”中给出的元素的光子相互作用部分的数值。
若用来获得线性吸收系数所使用的单胞体积、Z值或化学式总和(_chemical_formula_sum)与CIF中的不同，则会引起得到的数值与预测值之间的其他差异。记住化学式总和(_chemical_formula_sum)必须与存在的所有不同片段中所有元素的真实和相一致，包括任何溶剂以及所有H原子。如果由于省略少数H原子或溶剂原子而引起差异，则不对应于模型所暗示的内容。
若存在多个组分例如溶剂，或者其中一个组分具有无序或关于晶体学对称元素无序，则要确保在计算Z值、化学式总和(_chemical_formula_sum)以及线性吸收系数值时各组分的比例为正确且允许的。
例：ABSMU01_ALERT_1_A The ratio of given/expected absorption coefficient lies outside the range 0.90 <> 1.10
Calculated value of mu = 0.196
Value of mu given = 0.607
解决策略：按check计算的结果修改。
