[sdpd] racemic mixture

[ouyang...@mail.chem.tamu.edu]

Dear Friends,
How racemic mixtures are handled in Fullprof and GSAS? In single
crystal package such as shelxl97, the problem could be solved by adding
a twinning (law) card and refining the batch ratio. But how about
powder work? Do I have to refine them as two phases and set constraints
to tie all the atomic parameters together excepted the  scale factors?
Can somebody point me to published references? 
Thanks in advanced.

Xiang Ouyang Ph.D.
Department of Chemistry
Texas A&M University