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A very interesting thing happened when I did magnetic refinement, first of
all, I put in the parameters for Nuclear structure only, coz I want to have the
difference before putting magnetic phase, and then after this, everything is
ready for nuclear structure refinement, by convention, the scale factor is
initially set to 1. However, the refinement goes wrong, unacceptably, and if you
chose to "load new" then all the parameters go to weird values, which are
definitely wrong. I tried many time, the same would happen.
Then, I put an arbitrary scale factor, say, 100, the chi**2 factor finally
dropped to 161.xxx from 3456.xxx, wRp, and Rp are about ~56-78%, that means,
another go! Then I chose alternative arbitrary value, say, 300, cycle is 3, all
the damping factors are set to "0", the refinement dramatically goes well, and
giving rise to chi**2 about 8.103, wRp~13%, Rp~7%, refined scale factor is
~43267, having a look of liveplot, only one peak needing independently
unrefined, and some peaks occurred at nuclear peaks needing to be magnetically
refined to reach sensible intensities.
With these in mind, I tried many values, from 300 to 100, found the 120
seems to be kind of "critical value", when chose any (as much as I tried) value
greater than 120, the refinement goes well all the time, but any (as much as I
tried) smaller than 120, cannot do so, normally leading to oscillation in chi**2
factor? to verify this effect, I chose scale factor from opposite side, much
more greater than actual one, say 43267, i.e. 6789500, 34560000, the
refinement can go, and make some sense, finally givising rise to the chi**2
about 8.103, wRp~13%, Rp~7%.
Maybe the history can tell the future, when I encounter similar situation,
however, I still happy to know any consideration leading to explain this
trick?
P.S. when I then put in magnetic phase, similar thing happened, again, with
different specific value, and I didnt try the influence of damping factor, for
the time being.
Thanks for your check, at your convenient time
Lingfei,
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