Norberto wrote :
>This title is in perfect agreement with many papers claiming
>...the crystal structure has been solved by the Rietveld method...
>and (mostly) presenting RR's of isomorphous species with (some)
>ion replacement..
You may also find "structure determined by the Rietveld
method" in some paper titles or abstracts !
It is true that "to solve a structure" is less precise than
"to determine a structure". However, I would say that
both "to solve" or "to determine" associated with " a
structure by the Rietveld method" are nonsense (IMHO).
Only "to determine ab initio" is unambiguous (for me),
if not associated with "by the Rietveld method". You
may associate "to determine ab initio" with "by powder
diffractometry", which generally will include the Rietveld
method, since I do not know any recent "ab initio structure
determination" which did not made use of the Rietveld
method..
To agree with something wrong is not the best thing to do.
You and me know that "solved by the Rietveld method" is
only due to reviewers performing badly their job ;-). By definition,
the Rietveld method is the best structure refinement method
form powder diffraction data on the market, so far.
Anyway, possibly the D-092 conference will speak of
"Molecular replacement" (though this is used for proteins),
or "molecule location", which is the same : rotation and
translation of already known fragments (but "already known"
is not compatible with "ab initio" since you do not start from
scratch). Probably the Rietveld method will be applied
after each molecule move. If yes, the title could have been
more clear as "alternating molecule moves and Rietveld
refinement for structure determination". Though I doubt that
it will be usefull to perform Rietveld refinement cycles
before the molecule moves have led to a sufficiently
low Rp value... so that most of the time, it will even not
be the Rietveld method that will be used, but just a powder
pattern calculation.
And certainly, "ion replacement" is related to "molecular
replacement", at the lowest limit.
Not sure I was clear ?-).
Best
Armel Le Bail - Universite du Maine, Laboratoire des Fluorures,
CNRS ESA 6010, Av. O. Messiaen, 72085 Le Mans Cedex 9, France
http://www.cristal.org/
