Re: Philips PW1800 Geometry for Koalariet Rietveld?

Armel Le Bail ( armel@fluo.univ-lemans.fr )
Tue, 25 Nov 1997 14:42:26 +0100

At 02:58 25/11/1997 +1100, Lachlan wrote about koalariet:
>Obviously, I am a convert to this program and thus not an objective reviewer.
>A summary is that I believe if in the next few years, if programs don't use
>this (or a better) approach for Rietveld (rather than mathematical fits
>of present) they will be placed in the same bag as stone axes and flint
knives.

Mmmm, in this bag should be the programs which extract intensities from
single crystal data. Efforts were made in the past for using fundamental
parameters approaches which were not generalized : intensities are extracted
in rather simple antic ways. OK, there is no overlapping with single
crystals. Nevertheless the knowledge would have benefited of the
understanding why the single crystal profile shapes are sometimes also very
bizarre.

No I don't believe that the Koalariet approach will kill all other
empirical methods. The main objective will remain to determine and refine
structures whatever the profile shape approach. Only the final structure
is important for most users. So that you should first demonstrate that
the crystal structure coordinates are clearly better estimated. Has such
a proof been published or is in press ?

By the way, is Koalariet now able to extract structure factors for ab
initio structure determination ?

Obviously, I am not yet a convert to this program ;-).

Armel
Armel Le Bail - Universite du Maine - Laboratoire des Fluorures
CNRS UPRESA 6010 - Avenue O. Messiaen - 72085 Le Mans cedex 9 - France
Web : http://fluo.univ-lemans.fr:8001/