Hi,
Concerning the "phase composition". Exactly what is it used for?
> Dear Tao (and others),
> The phase fractions are proportional to "mole fraction unit cells" of each
> phase in the sample. They need not sum to unity but can be rescaled by hand
> if desired. The .lst file output from GENLES converts the phase fractions
> to wt. fractions based upon the actual atom types, positions and atom
> fractions given for each phase. The "phase composition" given elsewhere in
> the .exp file is not used for this purpose. If one has just two phases the
> best refinement strategy is to refine the histogram scale factor(s) and the
> two phase fractions with constraints that make them the same over all
> histograms and phases so that the sum of the phase fractions remains fixed
> at unity. If one has more than two phases and one histogram (usual case for
> x-ray diffraction) then fix the histogram scale to some convenient value
> (1.0 maybe) and vary all the phase fractions with no constraints. They will
> sum to some nonunitary value but the wt. fractions will be properly
> normalized by GENLES. For multiple histograms this same strategy still
> works. Fix the histogram scale and refine all the phase fractions
> independently.
> Bob Von Dreele
>
Jens Wenzel Andreasen "If only those geologists would let me
Dept. of Mineralogy alone, I could do very well, but those
Institute of Geology dreadful hammers! I hear the clink of
University of Copenhagen them at the end of every cadece of the
Phone: +45 33 25 20 60 Bible verses." - John Ruskin, 1851
