Author Topic: Choosing space group  (Read 233 times)

Eliyhau

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Choosing space group
« on: March 12, 2020, 01:43:23 PM »
Hello,
I am importing a CIF file to the iRaspa program, but for some reason the space group is not imported with it. According to Mercury software, the spacegroup should be C2/c, monoclinic; however, I cannot find it in the list of spacegroups under 'symmetry properties'.
Is there a way to get iRaspa to read the spacegroup directly from the CIF file? or perhaps a simple method to manually select the correct spacegroup?
Thanks!

David Dubbeldam

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Re: Choosing space group
« Reply #1 on: April 09, 2020, 08:42:02 AM »
For space groups, see http://cci.lbl.gov/sginfo/hall_symbols.html.
Hermann-Mauguin are not unique, the Hall symbol is.

C2/c is space group 15. You have the following flavors:

15:b1     C 1 2/c 1     -C 2yc
    15:b2     A 1 2/n 1     -A 2yac
    15:b3     I 1 2/a 1     -I 2ya
    15:-b1    A 1 2/a 1     -A 2ya
    15:-b2    C 1 2/n 1     -C 2ybc
    15:-b3    I 1 2/c 1     -I 2yc
    15:c1     A 1 1 2/a     -A 2a
    15:c2     B 1 1 2/n     -B 2bc
    15:c3     I 1 1 2/b     -I 2b
    15:-c1    B 1 1 2/b     -B 2b
    15:-c2    A 1 1 2/n     -A 2ac
    15:-c3    I 1 1 2/a     -I 2a
    15:a1     B 2/b 1 1     -B 2xb
    15:a2     C 2/n 1 1     -C 2xbc
    15:a3     I 2/c 1 1     -I 2xc
    15:-a1    C 2/c 1 1     -C 2xc                        <-----
    15:-a2    B 2/n 1 1     -B 2xbc
    15:-a3    I 2/b 1 1     -I 2xb