Magnetic refinements in Topas

ChrisRidley

I've been following the tutorial on LaMnO3 as my first attempt at magnetic refinements with Topas:
https://topas.webspace.durham.ac.uk/tutorial_lamno3_magnetic/

How does Topas the magnetic space group being different in symmetry to the nuclear structure? Is there some way to relate the two via a transformation as there is in fullprof where you can specify the transformation from the parent?

johnsoevans

This should all be covered in the magnetic tutorial. I think there's also a YouTube matching video.
In brief you have two options in TOPAS: a single phase to discribe nuclear and magnetic scattering; or a nuclear phse and separate magnetic-only phase. If you want to transform directly from a parent paramagnetic to a child magnetically ordered phase you can use the ISODISTORT description. By default that creates a combined nuclear and magnetic model, but you can edit it to be magnetic-only if it's more conveneint.

ChrisRidley

Thanks, John. I saw that. I just wondered if there was another way to formalise it in Topas, or whether it only took those three options. Will just work with ISODISTORT for now.