[sdpd] World record discussed

[Armel Le Bail <alb...@cristal.org>]

Hi,

Read in the latest Bruker-AXS journal ON SITE :

"Bridging the gap
The 441-atom oxide structure of Mo2P4O15
has been revealed....using... TOPAS."
Chem. Commun., 22, 2004, 2540-2540.

Crystallography upside down : single crystal
data better solved by using a powder data
simulated annealing software for direct space
SDPD.

But Mo2P4O15 has a superstructure enlarged from a
small model described with 11 atomic positions. Not
read the paper, and the ON SITE journal does not say it,
but we can guess that the 441 atoms in the
soperstructure were all positioned by extending
40 times the known small model, and then TOPAS
was used to shake a bit the system up to fit the
single crystal data. Or am I wrong ? If I am right, that
world record is not exactly equivalent to a complete
structure solution, it is something a bit different.
This is explained by the question : "Mo2P4O15 - has
the most complex oxide structure been solved with
the single crystal method ?" And the answer in the
publication was "yes and no".

May be a "yes and no and no" answer would be more
appropriate ;-).

Anyway, congratulations,

Armel

PS - World-class companies like to hold World Records...



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