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I landed on the wikipidia page where it shows that litharge it’s a tetragonal crystal of PbO and space structure P 4/n m m :1.
In the COD database I get multiple PbO CIF files, with different structures and space groups. Without the information from wikipidia I wouldn’t be able to identify the correct one just from the name.
I downloaded file COD ID 1010977 with space group P 4/n m m.space group IT number is 129
Pb and O positions are:
Pb1 Pb2+ 2 c 0. 0.5 0.24 1. 0 d
O1 O2- 2 a 0. 0. 0. 1. 0 dwe can check the coordinates of the Wyckoff number from Bilbao database (IT number 129: 2c, 2a)
2 c 4mm
(1/4,1/4,z) (3/4,3/4,-z)
2 a -4m2
(3/4,1/4,0) (1/4,3/4,0)However, they don’t match coordinates in the CIF file. Same information can be derived from CIF file COD ID 1537982.
Judging from the CIF files we can see these coordinates, which would belong to the Wyckoff letter k, with multiplicity 16:
_symmetry_equiv_pos_as_xyz
x,y,z
-x,-y,z
1/2+x,1/2+y,-z
1/2-x,1/2-y,-z
-x,y,z
x,-y,z
1/2-x,1/2+y,-z
1/2+x,1/2-y,-z
-y,x,-z
y,-x,-z
1/2-y,1/2+x,z
1/2+y,1/2-x,z
y,x,-z
-y,-x,-z
1/2+y,1/2+x,z
1/2-y,1/2-x,z
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