Re: refinement

L. Cranswick ( L.M.D.Cranswick@dl.ac.uk )
Mon, 6 Jul 1998 23:18:21 +0100 (BST)

To get a feel for what can be done, it can help running refining
on "known" similar samples to ones you intend to work with to get a
feel for how things might behave. For example, if you are working with
some iron silicates, obtain or synthesize some related iron(?) silicates
and work with them. Takes extra time of course but can be worth the
effort if you are going into new territory.

----

Also, access to template files for the Rietveld program you are using
can help during startup. Creating control files from scratch is
not fun.

One exception to this is the GUI LHPM being developed which has
a relatively easy start if you are used to programs with GUIs.
As with most Rietvelds - you can still do silly things if you
do not understand what you are doing - i.e., - refine on
special positions, set parameters to unrealistic values.
ftp://ftp.ansto.gov.au/pub/physics/neutron/rietveld/Rietica_LHPM95/
or via:
http://www.dl.ac.uk/CCP/CCP14/mirror/mirror.htm

Lachlan.

> >Can I refine atomic parameters(x,y,z,SOF,Uiso or U11,U22,....) with
> >rietveld refinement programmes(GSAS,Fullprof,WDBS) ?
>
> Kervan,
>
>
> Yes you can do all that and even more, but there are some traps.
>
> You should probably start to read the manual of GSAS or FullProf who cite
> the appropriate literature. If you are a real beginner, try to find someone
> who knows about the stuff or get the book "The Rietveld Method" edited by
> R.A.Young (IUCr Monographs on Crystallography #5, Oxford University Press,
> 1995, ISBN 0-19-855912-7) for introduction and details.
>
> If your access to internet is not too restricted, go to the websites given
> in Lachlan's and Armel's mails.
>
> Anyways - don't expect to get out of trouble before the end of 1998 if you
> try it all alone ;-)
>
> Sincerely
>
>
> Carsten
>
>
>
> Carsten Schinzer ---------------------------------------
>
> Institut de Chimie de la Matiere Condensee de Bordeaux
> 87, Avenue du Docteur A. Schweitzer
> F-33608 PESSAC
> fon +33 556 84 2650 (poste 7397) fax +33 556 84 2761
> http://www.icmcb.u-bordeaux.fr/~schinzer
> --------------------------------------------------------
>
> 

-- Lachlan M. D. CranswickCollaborative Computational Project No 14 (CCP14)    for Single Crystal and Powder DiffractionDaresbury Laboratory, Warrington, WA4 4AD U.KTel: +44-1925-603703  Fax: +44-1925-603124  E-mail: l.cranswick@dl.ac.uk   Ext: 3703  Room C14CCP14 Webpage (Under heavy reconstruction):   http://www.dl.ac.uk/CCP/CCP14/