checkCIF procedure

PROC-NAME: CELLV01 Type_1

PURPOSE: To check that the _cell_volume matches _cell_length_ and _cell_angle_ values.

PROCEDURE:

CALCULATE

S = { _cell_angle_alpha + _cell_angle_beta + _cell_angle_gamma } / 2

VOL = _cell_length_a * _cell_length_b * _cell_length_c * 2 *
SQRT { SIN [S] * SIN [S - _cell_angle_alpha ] * SIN [S - _cell_angle_beta ] * SIN [S - _cell_angle_gamma ] }

RV = _cell_volume / VOL

TEST

IF RV is 0.999 <> 1.001 issue ALERT A
   "Alert A The supplied cell volume differs from that calculated from the cell parameters. Ratio outside the range 0.999 < > 1.001"

There is a discrepancy between the unit cell volume given in the CIF and that calculated from the unit cell dimensions given in the CIF. Check the volume and cell dimensions for typographical errors.