I have a site disordered system, with multiple ions at particular site. I need to refine the occupancies maintaining the chemical formula and total occupany of 100% in fullprof. I tried giving constains and ended up altering the chemical composition on refinemnet. Please suggest how I could keep the formula intact and refine occupancies to understand the distribution of elements in the sites.
Refer to this description
http://ccp14.cryst.bbk.ac.uk/solution/gsas/constraint.html
You may also refer to the description of setting up the structure model in
Journal of Alloys and Compounds 368 (2004) 229–247
for a slightly different case than described above, but basically using the same methodology in a symmetry adapted fashion.
For constraining the site occupancy to 100%, this link may be useful:
https://www.researchgate.net/post/Full_Proff_how_to_encode_constraint_relations_for_refining_the_occupation_rate_of_the_Wyckoff_position_when_there_are_more_than_3_atoms_in_this_site/1
and for site disorder (split atom type approach) this link may be useful
https://www.researchgate.net/post/How_to_define_occupancy_in_FullProf_when_atoms_are_disordered_to_higher_multiplicity_positions
Thankyou so much Prof. Andreas Leineweber. Although I have no much experience with GSAS, these links contributed to my knowledge.
Thankyou Prof. Ashok Bhakar . I tried the method suggested by Dmitry-Chernyshov in the link provided by you. But my system is little complicated with 2 different sites and 3 different atoms arranging in these sites. Somehow, even after the said method, my composition is changing on refinement.
Can you help me in understanding how a combined XRD and Neutron refinement is possible in Fullprof.
An example file is given in FullProf with combined XRD & neutron diffraction refinement.
File name: pbb.pcr and data files name: PbSo4.dat, Pbsox.dat
I hope it may be helpful.
Thankyou Ashok Bhakar sir for the information. This was useful. This also helped me to explore different other examples in fullprof, which I was not aware.
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