RE: Extracting structure factors with GSAS

VONDREELE@mist.lansce.lanl.gov
Thu, 19 Dec 1996 9:50:59 -0700 (MST)

Dear Armel,
It is true that the initial F values for extraction in
GSAS are from a dummy atom (or partial structure). If
you place the atom at the origin then most space groups
will give the same value of F for all reflections. The
possibility of using a partial structure (molecular
fragment) will make the extraction better than one based
on equal structure factors and can help in completing a
structural model.
Bob Von Dreele