checkCIF procedure

PROC-NAME: DENSD01 Type_1

PURPOSE: To check that the _exptl_crystal_density_diffrn matches the _cell_volume and _chemical_formula_weight values

PROCEDURE:
CALCULATE

DEN = 1.66042 * _chemical_formula_weight * _cell_formula_units_Z / _cell_volume

RD = _exptl_crystal_density_diffrn / DEN

TEST
IF RD 0.9 <> 1.1 issue ALERT A
   "Alert A The ratio of the submitted crystal density and that calculated from the formula is outside the range 0.90 <> 1.10 "
RD 0.95 <> 1.05 issue ALERT B
   "Alert B The ratio of the submitted crystal density and that calculated from the formula is outside the range 0.95 <> 1.05 "
RD 0.99 <> 1.01 issue ALERT C
   "Alert C The ratio of the submitted crystal density and that calculated from the formula is outside the range 0.99 <> 1.01 "

The calculated density given in the CIF differs from that calculated using the specified formula weight and the stated number of formula units in the unit cell (Z). Check that (a) you have calculated the density correctly and (b) that _chemical_formula_weight and _cell_formula_units_Z are correctly specified. Remember that _chemical_formula_weight and the calculated density 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 and _chemical_formula_weight.