Hello
I have just rejoined the Rietveld mailing list, I used to be on the list when I worked
at Daresbury Laboratory but I left in 1995 when I moved to Cambridge to do a PhD in
chemistry. Now I am doing a postdoc at the number 2 university.
I have a problem with Fullprof. After I arrived in Oxford I was given some D2B data to
analyse with a magnetic component. I originally analysed the data using GSAS, the
magnetic component was refined as a separate magnetic phase in the spacegroup P-1. In
GSAS it is possible to refine the magnetic moment in the 3 crystallographic directions
with Mx, My and Mz as refineable parameters. However, we weren't sure in which
direction the magnetic moments were pointing.
I was told that using that other excellent piece of Rietveld software Fullprof that it
was possible to refine the magnetic moment as one moment and two angles (phi and
theta) rather than 3 moments in directions x, y, z therefore I decided to try redoing
the refinement in Fullprof to determine the moment and angles.
Looking at the Fullprof examples file for DyMn6Ge6 magnetic the following line is
given in the .pcr file when option JBT=-1 is chosen.
!Atom Typ Mag Vek X Y Z Biso Occ Rm Rphi Rtheta
! Im Iphi Itheta beta11 beta22 beta33 MagPh
Dy JDY3 1 0 0.00000 0.00000 0.00000 0.00000 0.33333 6.151 0.000 90.000
0.00 0.00 0.00 0.00 0.00 21.00 0.00 0.00
6.151 90.000 90.000 0.000 0.000 0.000 0.00000
21.00 0.00 0.00 0.00 0.00 0.00 0.00
Now I am stuck, I can guess what Rm, Rphi and Rtheta are but I don't know what the Im
Iphi Itheta beta11 beta22 beta33 MagPh parameters are and how they related to
Rm, Rphi and Rtheta. I haven't yet found out from the Fullprof manual what all of
these parameters mean. I guess that R and I refer to real and incommensurate
components but what betaxx and MagPh are I don't know. The structure that I am
refining is commensurate, how many of these terms can be left equal to zero?
Anyone out there in Rietveld-land know what these terms mean and what I need to do
next?
thanks tony.....
--
Dr. Tony Bell, Dept. of Inorganic Chemistry,
University of Oxford, South Parks Road, Oxford, OX1 3QR. 01865-272602
[EMAIL PROTECTED]
[EMAIL PROTECTED] http://www.shells.demon.co.uk/tonyweb.html
