Magnetic structure factor

mjcliffe

Is it possible to output the structure factor (i.e. F_hkl rather than |F_hkl|^2) for magnetic phases?

I've tried Out_A01_A11_B01_B11 but it seems to only output the structural component (or 0, for mag_only phases).
I'm using Topas Academic 6.

Thanks,

Matt

alancoelho

Hi Matt, I'm looking into it. I will get back to you asap.
alan

alancoelho

There's no direct way to get magnetic component of a phase. You can however use a switch as follows:

#define MAG_ONLY

str
#ifdef MAG_ONLY
mag_only_for_mag_sites
#else
' X-ray sites
site ...
#endif

site ... mlx @ .2 mly @ .4 mlz @ .2 ' magnetic site

Out_A01_A11_B01_B11(out.txt)

mjcliffe

Hi Alan,

Thanks for this - my issue was slightly different actually, sorry for being unclear! If I use Out_A01_A11_B01_B11(out.txt) with a magnetic phase, the magnetic component is ignored. That is to say, if I have a structural phase the output file is the same whether or not I have a magnetic component, and if I have a purely magnetic phase using mag_only, the file is filled with zeros. The output PND pattern does look correct, however, and has magnetic peaks.

Matt

mjcliffe

Hi Alan,

Sorry to bump this - is there any way to get the magnetic component to be outputted at all?

Matt

alancoelho

I think mag_only_for_mag_sites may have a problem. I am looking into it and thank for bringing it to my attention.

What is working is to put mag_only after each site; ie. this works:

site... mag_only
site... mag_only

mjcliffe

Hi Alan,

Thanks. I think there must be another issue as well:

even when I don't put mag_only/mag_only_for_mag_sites in, there is no magnetic contribution to the outputted structure factors. The numbers outputted are identical to the non-magnetic structure factors (where I set the moment to 0).

Best wishes,

Matt

mjcliffe

Hi Alan,

Could I ask what the status of this issue is? Were you able to sort it out?

Thanks and best wishes,

Matt

alancoelho

Hi Matt

I just checked and mag_only_for_mag_sites is working for Version 7. What Version are you using.
cheers
alan

mjcliffe

Hi Alan,

I'm using 6. The issue I found doesn't seem to be directly related to that the mag_only keyword used (it happens whether I include one or not).
My question relates to the fact that the structure factors A01 A11 B01 B11 do not seem to include magnetic components. Your earlier answer seemed to suggest they would - is this correct?

Matt

alancoelho

Hi Matt

I have been looking at outputting the magnetic intensity for Version 7; its difficult to do for Version 6. Can I ask what quantity you require; ie.

I can output a single number for each hkl, the magnetic intensity |Fmagcperp| as given in chapter "15. MAGNETIC STRUCTURE REFINEMENT" at http://www.topas-academic.net/Technical_Reference.pdf.

The intensity in total is given by:

A01^2 + B01^2 + Fmagcperp . Fmagcperp*

At present A01 and B01 includes the Rietveld scale parameter as well as multiplicity (but not scale_pks); |Fmagcperp| would also contain these factors.

Is this what you are after; probably best to contact me off the wiki.

cheers
alan

mjcliffe

Hi Alan,

Ah ok - if it's going to be very difficult that's fine, I can do this through non-Topas means! I hadn't realised that A01 etc. didn't include magnetism.

I was interested in the magnetic contribution to scattering which I think is Fmagcperp (not modulus or squared) in the Topas definitions. I was interested for polarised neutron measurements which is admittedly niche.

Thanks for clarifying this!

Matt