[ase-users] Error: invalid spacegroup

[Ask Hjorth Larsen]

Dear Zeyuan and Alessandro,

2017-12-01 14:18 GMT+01:00 Zeyuan Tang via ase-users
<ase-users at listserv.fysik.dtu.dk>:
> Dear Alessandro,
>
> Sometimes it's difficult to handle cif files in ASE. This is because the
> text format in cif files might vary from cif to cif. It's not realistic for
> ASE to deal with all different cifs, especially when they are downloaded
> from different databases.
> Here is a simple strategy to make it work. You can open your BTBT.cif and
> PBBTZ.cif in VESTA, then export these cifs to new cifs. The generated cifs
> are clean without unnecessary information and readable in ASE.

Apparently the symbols, e.g. P 21/a, are not known to ASE.  But VESTA
then converts it to a different symbol which ASE understands.

The question is, which spacegroup does P 21/a refer to, and is that
naming convention mandated by the CIF standard?

If someone knows the answer we can see whether something should be fixed.

Best regards
Ask

>
> Best regards,
>
> Zeyuan Tang
> Institute of Functional Nano and Soft Materials
> Soochow University
> 215123, Suzhou, China
> Email: zeyuan.tang at outlook.com
> Website: tangzeyuan.com
>
> ________________________________
> From: ase-users-bounces at listserv.fysik.dtu.dk
> <ase-users-bounces at listserv.fysik.dtu.dk> on behalf of Landi, Alessandro via
> ase-users <ase-users at listserv.fysik.dtu.dk>
> Sent: Friday, December 1, 2017 18:43
> To: ase-users at listserv.fysik.dtu.dk
> Subject: [ase-users] Error: invalid spacegroup
>
>
> Hello everyone.
>
> I am a PhD student in chemistry at the University of Liverpool and a new
> user of ASE.
>
> Unfortunately, I am experiencing a problem when I try to read some cif
> files, for example the two attached that I downloaded from the Cambridge
> Cristallographic Data Centre.
>
> When calling "ase.io.read" on one of these files, I get the following error:
>
> ase.spacegroup.spacegroup.SpacegroupNotFoundError: invalid spacegroup ###,
> setting 1 not found in data base
>
> Where ### is the spacegroup name, "P2(1)/n" for PBBTZ.cif and "P21/a" for
> BTBT.cif
>
> I am not a CIF expert, so could someone please explain me why these groups
> are not recognized by ASE?
>
> Thank you in advance for your help.
>
> Regards,
> Alessandro
>
>
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