[ase-users] Bug in spacegroup 154

[Jesper Friis]

Hi again, the symmetry for spacegroup 154 in lattice/spacegroup/spacegroup.dat is in accordance with International Tables, so I don't think we should change it.

Maxime, I think your problem is that the symmetry in your cif-file is not consistent with International Tables, see the below screenshot. I guess that the best solution might be to change the cif reader to use the symmetry operations given in the cif-file.

Regards
/Jesper

[cid:image001.png at 01D16B2E.363E3850]

From: Jens Jørgen Mortensen [mailto:jensj at fysik.dtu.dk]
Sent: Friday, February 19, 2016 10:16
To: Maxime van den Bossche <maxime.vandenbossche at chalmers.se>; ase-users at listserv.fysik.dtu.dk; Jesper Friis <jesper.friis at sintef.no>
Subject: Re: [ase-users] Bug in spacegroup 154

On 02/18/2016 10:53 AM, Maxime van den Bossche wrote:

Hello!

I came across a bug when trying to read in the following
quartz SiO2 structure (in CIF format), which belongs
to the P 32 2 1 spacegroup (number 154).

http://rruff.geo.arizona.edu/AMS/CIF_text_files/00859_cif.txt

The number of atoms, as well as atomic positions in the resulting
Atoms object are incorrect, and it seems to be due to errors in
the way the spacegroup's symmetry operations are defined.

The last three lines in the "symmetry operations" block
of the entry 154 in /ase/lattice/spacegroup/spacegroup.dat
are as follows:

    0  1  0     1  0  0     0  0 -1    0.0000000000  0.0000000000  0.0000000000
    1 -1  0     0 -1  0     0  0 -1    0.0000000000  0.0000000000  0.3333333333
   -1  0  0    -1  1  0     0  0 -1    0.0000000000  0.0000000000  0.6666666667

but the symmetry translations should be corrected to:

    0  1  0     1  0  0     0  0 -1    0.0000000000  0.0000000000  0.6666666667
    1 -1  0     0 -1  0     0  0 -1    0.0000000000  0.0000000000  0.0000000000
   -1  0  0    -1  1  0     0  0 -1    0.0000000000  0.0000000000  0.3333333333

After this fix, I got the quartz structure I expected.

Thanks!  Anyone know where the spacegroup.dat file in ASE comes from?

Jens Jørgen


Regards,
Maxime




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