PROC-NAME: CHEMW01 Type_1

PURPOSE: To check that the _chemical_formula_weight matches that calculated for the _chemical_formula_sum.

PROCEDURE:

SUMMATION

(1) match the element symbols in _chemical_formula_sum

with values for _atom_type_symbol [NOT USED]

(2) multiply the number of atoms in _chemical_formula_sum

by the mass for this element

CALCULATE

RW = _chemical_formula_weight / SUM of (2)

DW = | _chemical_formula_weight - SUM of (2)|

TEST

IF RW

0.90 < > 1.10 issue ALERT A (> 10% difference)

? ? ? ? ?"Alert A The ratio of given/expected molecular weight as calculated from the _chemical_formula_sum lies outside the range 0.90 <> 1.10 "

0.95 < > 1.05 issue ALERT B (> 5% difference)

? ? ? ? ?"Alert B The ratio of given/expected molecular weight as calculated from the _chemical_formula_sum lies outside the range 0.95 <> 1.05 "

0.99 < > 1.01 issue ALERT C (> 1% difference)

? ? ? ? ?"Alert C The ratio of given/expected molecular weight as calculated from the _chemical_formula_sum lies outside the range 0.99 < > 1.01 "

IF DW > 1.0 and category is FO, FM, CO or CM

issue ALERT C

? ? ? ? ?"Alert C The difference between the given and expected weight for compound is greater 1 mass unit. Check that all hydrogen atoms have been taken into account."

? ? ? ? The formula weight given in the CIF differs from that calculated using the formula in _chemical_formula_sum. Check that (a) you have calculated the formula weight correctly and (b) that _chemical_formula_sum is correctly and fully specified. Remember that _chemical_formula_sum and _chemical_formula_weight 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 formula weight.

? ? ? ? _chemical_formula_sum must also be in the correct format (e.g. do not use subscript formatting: C10 H20 is correct, C~10~ H~20~ is not).

(http://journals.iucr.org/services/cif/checking/CHEMW_01.html)

目的: 檢查分子量(_chemical_formula_weight)與從化學(xué)分子式總和(_chemical_formula_sum)計算的結(jié)果是否一致。

若RW小于0.90或大于1.10(即大于10%的誤差)，則發(fā)布A類警告

? ? ? ?? "Alert A The ratio of given/expected molecular weight as calculated from the _chemical_formula_sum lies outside the range 0.90 <> 1.10 "

若RW小于0.95或大于1.05(即大于5%的誤差)，則發(fā)布B類警告

? ? ? ?? "Alert B The ratio of given/expected molecular weight as calculated from the _chemical_formula_sum lies outside the range 0.95 <> 1.05 "

若RW小于0.99或大于1.01(即大于1%的誤差)，則發(fā)布C類警告

? ? ? ?? "Alert C The ratio of given/expected molecular weight as calculated from the _chemical_formula_sum lies outside the range 0.99 < > 1.01 "

若DW大于1.0并且類別為FO、FM、CO或CM，則發(fā)布C類警告

? ? ? ?? "Alert C The difference between the given and expected weight for compound is greater 1 mass unit. Check that all hydrogen atoms have been taken into account."

? ? ? ? CIF給出的分子量與從化學(xué)分子式總(_chemical_formula_sum)和計算得到的結(jié)果不一致。則檢查(a)是否正確地計算了分子式，(b)是否正確并完整地給出了化學(xué)分子式總和(_chemical_formula_sum)。記住化學(xué)分子式總和(_chemical_formula_sum)與化學(xué)分子量(_chemical_formula_weight)必須和存在的不同部分中所有元素的真實總和一致，包括任何溶劑和所有氫原子。如果是由于刪除了少許氫原子或溶劑原子而導(dǎo)致的差異，則不對應(yīng)于模型所暗示的內(nèi)容。

? ? ? ? 若存在多個組分例如溶劑，或者其中一個組分具有無序或關(guān)于晶體學(xué)對稱元素?zé)o序，則要確保在計算Z值和化學(xué)式總(_chemical_formula_sum)時各組分的比例為正確且允許的。

? ? ? ? 化學(xué)式總和(_chemical_formula_sum)必須使用正確的格式(例如不要使用下標(biāo)格式：C10 H20是正確的格式；而C~10~ H~20~是錯誤的格式)。

例：CHEMW01_ALERT_1_A The ratio of given/expected molecular weight as calculated from the _chemical_formula_sum lies outside the range 0.90 <> 1.10

Calculated formula weight = 585.3216

Formula weight given = 1324.8300

警告原因：分子式不對。

解決策略：在ins里給對分子式和Z值重新精修生成CIF。若使用Olex2軟件，則可填好Z'后精修重新生成CIF即可。