CheckCIF-CELLV02

PROC-NAME: CELLV02 Type_1

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

PROCEDURE: (Ref: Giacovazzo Fundamentals of Crystallography p.122)

CALCULATE

CSA = COSINE[_cell_angle_alpha]

CSB = COSINE[_cell_angle_beta]

CSG = COSINE[_cell_angle_gamma]

SA = SINE[_cell_angle_alpha]

SB = SINE[_cell_angle_beta]

SG = SINE[_cell_angle_gamma]

A1 = (su of a)/_cell_length_a

A2 = (su of b)/_cell_length_b

A3 = (su of c)/_cell_length_c

B1 = SA*(CSA-CSB*CSG)*(su of alpha)

B2 = SB*(CSB-CSA*CSG)*(su of beta)

B3 = SG*(CSG-CSA*CSB)*(su of gamma)

CV = [(_cell_length_a*_cell_length_b*_cell_length_c)**4/(_cell_volume)**2]

SUVOL = SQRT{(_cell_volume)**2*(A1**2+A2**2+A3**2)+CV*(B1**2+B2**2+B3**2)}

DSUV = |{su of cell volume}-SUVOL|

TEST

IF DSUV > 8 issue ALERT A

        "Alert A The supplied cell volume s.u. differs from that calculated from the cell parameter s.u.'s by > 8"

DSUV > 4 issue ALERT B

        "Alert B The supplied cell volume s.u. differs from that calculated from the cell parameter s.u.'s by > 4"

DSUV > 2 issue ALERT C

        "Alert C The supplied cell volume s.u. differs from that calculated from the cell parameter s.u.'s by > 2"

        There is a discrepancy between the standard uncertainty (s.u.) for the unit cell volume given in the CIF and that calculated from the s.u.s of the unit cell dimensions given in the CIF. Check the volume and cell dimension s.u.s for typographical errors (rule of '19' applies).

(http://journals.iucr.org/services/cif/checking/CELLV_02.html)

目的：检查单胞体积(_cell_volume)标准不确定度(s.u., standard uncertainty)与单胞长度(_cell_length_)和单胞角度(_cell_angle_)的标准不确定度是否相符。

若DSUV大于8，发布A类警告

        "Alert A The supplied cell volume s.u. differs from that calculated from the cell parameter s.u.'s by > 8"

若DSUV大于4，发布B类警告

        "Alert B The supplied cell volume s.u. differs from that calculated from the cell parameter s.u.'s by > 4"

若DSUV大于2，发布C类警告

        "Alert C The supplied cell volume s.u. differs from that calculated from the cell parameter s.u.'s by > 2"

        CIF中单胞体积的标准不确定度和通过单胞尺寸的标准不确定度计算得到的数值不相符。检查单胞体积和单胞尺寸的标准不确定度是否存在排版错误。

解决策略：一般不会出现这种情况，检查是否晶胞参数输入错误。