The use of Shubnikov symmetry is very limited because a lot of magnetic structures (even commensurate ones) are possible that cannot be well described by it. Better descriptions of symmetry-allowed structures are given by using 'representational analysis' (or for the serious few- corepresentational analysis). I wrote a program SARAh that performs these calculations in a couple of clicks and clips onto GSAS (and Fullprof). All you have to do is make a P1 magnetic-only phase (so no red/black) and SARAh will use reverse-Monte Carlo cycling to let you refine the different possibilities. You can download SARAh (works under windows) from ftp.ill.fr/pub/dif/sarah/
If you have any questions, I would be happy to help.
Andrew
----------------------------------------------------------------------
Dr. Andrew S. Wills,
Dept. of Chemistry,
Christopher Ingold Laboratories,
University College London,
20 Gordon Street,
London,
WC1H 0AJ,
UK.
Tel: +44 (0) 20 7679 4537
Fax: +44 (0) 20 7679 7463
Email: [EMAIL PROTECTED]
http://www.chem.ucl.ac.uk/people/wills/
-----------------------------------------
On 17 Jan 2005, at 19:51, Maxim V. Lobanov wrote:
whilst the red/black color in GSAS make no strong sense to meAs far as I understand, the spin-flip model in GSAS is equivalent to
Shubnikov symmetry with "red color" meaning primed element.
There was a more detailed description of how it works on the list in the
message by Elad Caspi (quite long time ago) - you can try to find it in
the list archive...
Sincerely,
Maxim.
_______________________________________
Maxim V. Lobanov <[EMAIL PROTECTED]>
Department of Materials Science and Engineering
University of Tennessee
101 South College
1413 Circle Dr.
Knoxville, TN 37996
Dear Rietveld lister,
Sorry for interpreting at this moment, I am going to use GSAS to treat the
commensurate magnetic structure for the first time which data doesnt come
from tutorials so on, as suugested from my group chaps, GSAS employs the
crystal space group rather than much more complicated magnetic symmetry to
deal with atoms in aymmetric unit cell, plus spin flip color model, or colr
model to fiter the magnetic atoms eventually construct whole magnetic atomic
position and its orientation within in Unit cell, which is ready to be
taking into account for Magnetic refinement.
However, the problem is I dont find apparent source to know how to consider
the create the magnetic model using spin flip, whilst the red/black color in
GSAS make no strong sense to me, therefore I would collect any suugestion
and experience from here to have a immediate go.
many thanks to you,
with best regards
Ling Fei
Salford Univeristy,
M5 4WT
