Matteo,
I would go in and check the listing to see what restraints that GSAS
'thinks' it has for the angles. If the distance between atoms are more
than 2 angstroms or so, sometimes GSAS does not 'see' them and therefore
they don't end up being restrained in the refinement. After you load the
restraint you can type 'l' to get a list of the restraints that GSAS
found in your structure. Could be something else, but that is where I
would start.
-Jennifer Doebbler
Matteo Zoppi wrote:
Dear Rietvelders,
does anyone please let me know if there are some mistakes one can do
when trying to use both bond lengths and angles restraints in GSAS? It
is probably something trivial. I can't find why, when I try to refine
a structure (monoclinic or triclinic) with bond angles restraints on
the octahedral positions of oxygen, the bond distances restraints work
perfectly but bond angles restraints don’t. I restraint bond angles of
oxygen-metal-oxygen to 90(3) with a high FACTR but apparently these
values are not retained and shift to mach smaller of bigger values.
Initial starting values are within the correct range, and restraints
are put on atoms within close bonding distance of each other.
Thank you for your help.
Matteo
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Dr. Matteo Zoppi
Museo di Storia Naturale - Sezione di Mineralogia
Università degli Studi di Firenze
Via G. La Pira, 4 – 50121 Firenze, ITALY
Tel. +39 055 2756340
[EMAIL PROTECTED]
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