[GSAS-II] Constraining a mixed site in a rigid body [SEC=UNCLASSIFIED]

[AUCKETT, Josie]

Dear all,

I have defined a rigid body containing a mixed occupancy site, i.e., two sites with the same coordinates and complementary occupancy. When I match up the rigid body to my phase it only locks one of the mixed sites to the rigid unit, even though both sites are defined in the rigid body XYZ file and also on the Atoms tab for the phase. This would be fine if I could constrain the x/y/z/Uiso/Frac parameters of the uncaptured site to the captured one, but the usual constraints one would apply to a mixed site don't seem to work - so if I refine the rigid body angle the uncaptured atom doesn't move with its partner, regardless of the combination of refine flags I set on the Atoms tab (and certain combinations cause GSAS2 to warn that constrained parameters are not being refined together).

Can anyone advise how to achieve mixed occupancy in a rigid body? I don't mind whether the solution involves constraints or including both sites in the rigid unit.

Thanks in advance,
Josie


Dr Josie Auckett
Postdoctoral Researcher
Australian Centre for Neutron Scattering
Australian Nuclear Science and Technology Organisation
Tel
Email
Web

+61 2 9717 3601
josiea at ansto.gov.au<mailto:josiea at ansto.gov.au>
http://www.ansto.gov.au/acns/


[ansto]


Important: This transmission is intended only for the use of the intended addressee. It is confidential to the intended addressee and may contain privileged information and or copyright material. If this email is not intended for your attention, any use, printing, storage , reproduction or further disclosure of this communication (including all attachments) is strictly forbidden. If you have received this transmission in error, please notify me by telephone or email and immediately delete all copies of this transmission as well as any attachments.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.aps.anl.gov/pipermail/gsas-ii/attachments/20170124/9a634436/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.jpg
Type: image/jpeg
Size: 5561 bytes
Desc: image001.jpg
URL: <http://mailman.aps.anl.gov/pipermail/gsas-ii/attachments/20170124/9a634436/attachment.jpg>