[sdpd] Human not needed ?

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

Hi,

April review.

Just received today by ealert the Contents of Journal of
Applied Crystallography (June 2003), AND the full paper
version of Journal of Applied Crystallography (April 2003).
This shows an exact 2 months difference in the speed
of information distribution with or without the Internet...

Many papers interesting SDPD in that April J. Appl. Cryst. :

- pages 193-205 : Its is said that "The last step of a
crystal structure determination that requires human
intervention is the interpretation of Fourier maps..."
and the authors have incorporated in DIRDIF a completely
automatic algorithm for the Fourier map analysis.
Comment : Well, the authors have no idea about the
human interventions in a SDPD...

- pages 230-238 : "Solution of organic crystal structures
from powder diffraction by combining simulated annealing
and direct methods".
Again, a step is made in the direction of automation. "The
procedure is completely automatic and has been included in
EXPO."
Comment : among the validation tests is the tetracycline
hydrochloride of the 1998 SDPD Round Robin - which can
finally be solved now by using EXPO, though with more
difficulty (but automatically solved, thus meaning only longer
CPU time) than the for other tests.

- Pages 239-243 : "A Monte Carlo approach to crystal
structure determination from powder diffraction data".
Comment : availability of the software ?

Pages 286-294 :"Instrument line-profile synthesis in high-
resolution synchrotron powder diffraction."
Comment : NAC (Na2Ca3Al2F14) better (with less size/
strain broadening) than LaB6 NIST SRM 660 ! The revenge
of the Fluoride Lab !-).
Second comment : this is not be verified by using conventional
X-ray and a Bragg Brentano reflexion geometry - and the conclusion
is that the universal reference compound does not exist -
but this is only my own conclusion, there is not a word in
the paper about that.

Pages 326-332 : "Structural refinements of the individual grains
within polycrystal and powders."
Comment : Wow ! 1500 grains of Al2O3 with average 20µm size,
100680 diffraction spots identified with a CCD detector, structure
of 57 of the largest grains refined independently !
Well, no need for humans, and no need for a powder
diffractometer : do it all with a single crystal diffractometer !

Pages 356-365 : "X-Cell: a novel indexing algorithm for
routine tasks and difficult cases."
Comment : Commercial inside Reflex Plus (Accelrys).
If you can afford it, that's fine for you.

If someone wants to review the June 2003 J. Appl. Cryst.
with the SDPD lorgnette side, thanks. No automatic review
system already existing so that we, humans, can continue
to reproduce ourself ;-).

Armel

PS - And do not forget to upload your CIFs at the COD
(8000 entries now) :    www.crystallography.net


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