Dear Mr. Werner,
this sounds for me like that there would be a problem in GSAS. If you
look to the formulas at page 155 of the GSAS manual, in all
trigonal/rhombohedral Laue groups there is no separate S004 for
rhombohedral settings (in fact S400 = S004). But for the hexagonal
settings (not explicitly mentioned in the manual), S310 does not occur
as refinable parameter, because S310 (associated with h^3k) is symmetry
related to S400. Thus h^3k appears with S400. Only S301 is refinable for
Trigonal -3 and -3m (but not for 6/m and 6/mmm, where it is 0). At the
moment it appears to me that there may be something wrong in the
program. The formulas in the manual appear in principle o.k to me (I
went through these formulas by myself some years ago), but the
parameters which GSAS/EXPGUI seems to use seem to contradict themselves.
This also is in agreement with the Stephens (1999) paper. But please
tell me if I got something wrong....
Best regards
Andreas Leineweber
Franz Werner wrote:
Dear Mr Leineweber
actually I am wondering about your parameters. May it be that S310 is
instead S301??
If the former is the case, you use the hexagonal setting,
which I would also expect if you use also the hexagonal setting for the
crystal structure.
Thanks for your comment. I just checked the parameter names on EXPGUI's
"Profile" tab again: S400, S004, S202 and S310 (SG R-3, hexagonal setting).
Regards
Franz Werner
