[sdpd] Re: Scratch

[Armel Le Bail <armel... @fluo.univ-lemans.fr>]

Of course, proper indexation is the condition sine qua non.
Ito, Dicvol and Treor are already extremely reliable. Using 
all of them ensure you evenmore success. The problem is
that they work wonderfully only with wonderful data. I have
heard about many other software and even recent use of
Monte Carlo for indexing. That those software are more
comfortable with bad starting data than Ito, Dicvol and Treor,
I do not believe it. Then, the state of the art, in my opinion, 
continue to be the simultaneous use of Ito, Dicvol and Treor.
The biggest problem on which you have little influence is 
your sample purity. Not being sure of the purity is sufficient
for discouraging many researchers to adopt powder
diffraction ;-).

Armel

Original mail :
From: Gregory A Stephenson <STEPHENSON_GREGORY_A... @LILLY.COM> 

>Although molecular finding methods may be considered a not so useful technique
>since "the structure" is already known from NMR or mass spectrometry (or a
>chemist who actually has a reasonable idea of a few possibilities of what he
>has synthesized-which is fortunately generally the case).  It still appears to
>me that in the event that you can rely on the latter, you still need the basic
>starting point-proper indexation.  I use the standard Ito, Dicvol and Treor
>programs; each being very good-but indexation still seams to be more limiting
>than the monte carlo/simulated annealing approach to solution.  What is the
>state of the art?  Is there something more reliable than these programs for
>low symmetry organic molecules?