Dear Irvin,
You seem to be wanting to put in a special form factor for your D2
molecule. In GSAS special form factors need special element names -
these are "QA", "QB", ... Then use this name for the atom "type" for
your D2 & put in just one of these. If it failed let me have a look at
your .EXP file.
Best,
Bob Von Dreele
R.B. Von Dreele
IPNS Division
Argonne National Laboratory
Argonne, IL 60439-4814
-----Original Message-----
From: Telepeni Irvin [mailto:[EMAIL PROTECTED]
Sent: Wednesday, November 28, 2007 8:28 AM
To: rietveld_l@ill.fr; rietveld_l@ill.fr
Subject: RE: How to add a molecule in GSAS?
Hi,
I finally managed to find out how to put a D2 molecule in GSAS.
Rather than having one D with the double of the scattering length, it
was recommended to do as following in the GSAS news(2002 march: I
entered the form factor of D2 molecule as a table of sin(theta)/lambda
VS form factor (from a .txt file) (expedt: Y + L + F + N + QA + R + U).
This option seems only valid for free rotor (CH$ and H2 ...) But while
GSAS reads (but does not plot) the new form factor from the file, but
it does not recognise the new "atom type" as a standard atom when I try
to add the corresponding atom. Have I missed something?
Cheers
Irvin
-----Original Message-----
From: AVDEEV, Maxim [mailto:[EMAIL PROTECTED]
Sent: Mon 08/10/2007 23:58
To: rietveld_l@ill.fr
Subject: RE: How to add a molecule in GSAS?
Irvin,
With GSAS discrete D2 molecules can be modeled using rigid body
constraints:
http://www.ccp14.ac.uk/solution/gsas/rigid_bodies_gsas.html
http://www.ccp14.ac.uk/ccp/web-mirrors/ian-swainson/fireside_fuide_to_ri
gid_bodies.pdf
If the molecules are rotationally disordered you might try
special form
factors (like spherical shell one implemented in Fullprof)
http://www.ill.fr/dif/Soft/fp/index.html
In the extreme case of disorder you may also try to model
continuous
distribution of scattering density with Maximum Entropy Method
(for
example with Rietan+Prima)
http://homepage.mac.com/fujioizumi/rietan/angle_dispersive/angle_dispers
ive.html
Cheers,
Max
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