CIF files

[pcpatfire]

Hi,
Is there a way using diffpy.structure to save a CIF with the correct space group instead of using 'P 1'?

[sbillinge]

Thanks for the question @pcpatfire

I am asking around about this, but I think it may be hard if symmetry breaking distortions have been introduced in the modelling. In that case we would have to run the resulting structure through a program that tries to determine space group symmetry from the coordinates.

What is your use-case? Do you just want a round-trip, so a CIF is read in, run through PDFgui/diffpy-cmi and then output without breaking symmetry? Or you want a tool that "finds" the highest new symmetry after allowing distortions?

[pcpatfire]

Thanks for your answer.
I would like to use the resulting CIF to calculate the diffraction pattern (using for instance pymatgen).

[pcpatfire]

Another simple question. Is the information stored in the spacegroup variable while reading the CIF file saved anywhere after creating the structure? Is it accessible after loadind a CIF'

[dragonyanglong]

Hi @pcpatfire , you can use the cif parser to access the spacegroup info, For example:

from diffpy.structure.parsers import p_cif
a =  p_cif.P_cif()
a.parseFile('Ni.cif')
a.spacegroup.crystal_system

[sbillinge]

This would be a useful feature, but will take some work, so moving it forward for now. There is software that will find symmetries in files within certain resolutions and we can look into doing that.