>I think the best way to do incommensurate structure is Jana.
>Peter

Dear Peter, 
Thank you very much. I agree completely, and I used Jana several times - it
is really good and convenient. It is simply faster for me to work with
Fullprof (matter of experience). I could see also one "disadvantage" in
using Jana for this particular purpose:
It requires you to specify the superspace group (am I right?) - I can do
that and also (for the preliminary identification of the wavevectors)
choose one with no systematic extinctions on m. But in certain groups the
possible direction of the modulation wave vector is determined uniquely by
symmetry (e.g., 001 in many tetragonal groups). So, in order to generate
other modulation vectors one needs to go to e.g. orthorhombic subgroups and
their superspace group, which is of course possible, but could be quite
time-consuming. It probably means that there is small distortion of the
basic cell, but it is not required to fit the pattern (the improvement is
marginal, if any). So I wanted some program that would allow me to specify
a (3D) space group, an arbitrary modulation vector and to do a Le Bail fit,
and I was thinking of Fullprof first (because of personal experience). I
tried to do that in Fullprof, but failed to find a correct procedure, and
after quite careful reading the manual started to doubt if the one exists.
I would greatly appreciate any advices/comments/suggestions.
Sincerely,                                      Maxim.


__________________________________
Maxim V. Lobanov
Department of Chemistry
Rutgers University
610 Taylor Rd
Piscataway, NJ 08854
Phone: (732) 445-3811

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