I just can't seem to keep away from these R-Bragg questions! :-)
(An interesting finding based on the previous discussion is the R-Bragg
calculation in the software I am using is affected by background
(thus something dodgy must be going on) while Fullprof seems to be
doing the right thing and not including background in the calculation
of the R-Bragg. Not sure about other software as yet?)
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Does anyone know the pros and cons of refining of Weighted R-Bragginstead of the Weighted Profile (R-Wp)? Are there any packagesout there that can be toggled to refine on a weighted R-Bragg rather than R-Wp?
In the paper by H Boysen (Anharmonic Thermal Parameters, Disorder andPhase Transitions - NIST Special Publication 846. Proceedings of theinternational conference Accuracy in Powder Diffraction II, held at NIST,Gaithersburg, MD, May 26-29, 1992 (Issued October, 1992) pg 165-174))it mentions how when refining these additional parameters how the conventional GOF is only slightly changed but that "a much larger effect may be obtained, if one uses a weighted Bragg R-factor."
Using the LHPM/REIT7/SR5 software, occassionly when refining subtle parameters such as site occupancies or thermal parameters, the R-Wp can go down while the R-Bragg goes up. Are then any comments on this as it implies at this level - it would be better to be refining and minimising on the weighted R-Bragg, not the weighted profile(?).
Thanks in advance,
Lachlan.
Lachlan Cranswick - Melbourne, Australia _--_|\ Phone/Fax : (613) 9455-1345 / \E-mail : lachlan@melbpc.org.au \_.--._/Mobile Phone/Voice Mail : 0412-1141-31 vCrystallographic WWW : http://www.unige.ch/crystal/stxnews/stx/volnteer.htm