[sdpd] CCP14/RIET: Restrained Rietveld Refinement of Organics tutorials page

["L. Cranswick" <L.M.D.Cranswick...@dl.ac.uk>]

Based on the problems people described at the Bayreuth
Powder workshop, there is a draft webpage on 
  "Restrained Rietveld Refinement or Organics" 
presently based around the Laboratory Powder X-ray Tetracycline 
Hydrochloride data used for the structure solution
round robin (SDPDRR):

 http://www.ccp14.ac.uk/solution/restrained_rietveld/

Using:
  Crystals for Windows for DLS modelling and generating
    the bond-length, bond-angle, planar restraints that 
    can be passed onto various Rietveld software that have
    these options.

   http://www.ccp14.ac.uk/solution/restrained_rietveld/dlscrystals.html
 
  GUI WinORTEP to view the structure as it is refining and routinely
    obtain bond-lengths and angles
    (GUI WinORTEP can open Shelx, CIF GSAS, Fullprof, LHPM-Rietica
     and a variety of other formats)

Examples:

  GSAS (using also the EXPGUI interface)  and  Fullprof

   http://www.ccp14.ac.uk/solution/restrained_rietveld/restrain_gsas.html

   http://www.ccp14.ac.uk/solution/restrained_rietveld/restrain_fullprof.html

-----

As there could be errors and dodgy suggestions in the
pages, corrections, suggestions and tricks appreciated.

Lachlan.

PS:  A few queries:

What are the restraint options available in the
various Rietveld programs?  GSAS seems to have
the option for bond-length - bond-angle - planar
and torsion angle restraints.
Most other Rietveld programs with restrain options 
seem limited to just bond-length restraints?

My impression is that bond-angle and planar restraints
are also very useful in keeping a refinement physically
meaningful(?)

Are there any Rietveld programs out there that can 
insert "riding" hydrogen restraints for correct 
handling of placed hydrogens during the refinement?

-- 
Lachlan M. D. Cranswick

Collaborative Computational Project No 14 (CCP14)
    for Single Crystal and Powder Diffraction
Daresbury Laboratory, Warrington, WA4 4AD U.K
Tel: +44-1925-603703  Fax: +44-1925-603124
E-mail: l.cranswick...@dl.ac.uk  Ext: 3703  Room C14
                           http://www.ccp14.ac.uk


-------------------------- eGroups Sponsor -------------------------~-~>
eGroups eLerts
It's Easy. It's Fun. Best of All, it's Free!
http://click.egroups.com/1/9698/14/_/40740/_/972584504/
---------------------------------------------------------------------_->