Hello Arie,
You have to set the same parameter number for gama and a.
for instance for Al2O3:
! a b c alpha beta gamma
4.771113 4.771113 13.027040 90.000000 90.000000 120.000000
81.00000 81.00000 91.00000 0.00000 0.00000 81.00000
gama is kept fixed to 120�.
At 10:51 15/06/2001 +0200, you wrote:
>Hi all,
>
>I have a problem concerning the refinement of the cell parameters of a
>rhombohedral space group (R-3c) in Fullprof. The documentation says to use
>the hexagonal description of the unit cell and that is what I do: a=b, c,
>alpha=90, beta=90, gamma=120. a and b are the refinable parameters, the
>angles should be kept fixed.
>
>The program tries nonetheless to refine the gamma angle although its code
>is set to zero. The output shows however that the associated standard
>deviation is equal to zero.
>The total number of parameters is four in profile matching mode with
>constant relative intensities (jbt=3): one scale factor, one zero error and
>two cell parameters (a and b). The profile parameters are kept fixed for
>the moment.
>
>Who recognises this problem? Thanks in advance.
>
>Arie van der Lee
>
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Patrick Weisbecker
Service commun diffraction X
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