Re: [sdpd] determine lattice parameters..

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

Hi,

Commercial or Academic software, that is the question.

Round robins are supposed to establish which software
is efficient. However, this requires that all software
producers compete, not always the case...

About indexing (determining lattice parameters), the tradition
to share openly source codes and executables is still in use
for a large series of programs. Moreover, it is not recommended
to restrict yourself to the use of only one program. See the
Indexing Round Robin results there :
http://www.cristal.org/uppw/benchmarks/
Note that some manufacturers provide indexing programs
which are exactly the same as those freely available ones,
embedded into some Graphical User Iinterface (for example
X'Pert Highscore Plus from Panalytical, including ITO,
TREOR, DICVOL and McMaille). If the GUI does not
seem absolutely essential to you, then grab those academic
programs for free. Some packages are able to prepare
data for them (WinPlotr for instance) after peak position
hunting.

About structure solution now :
- direct methods : EXPO is freely available and has no
   competitor (it can realize the whole SDPD steps but contains
   only one indexing software : N-TREOR)
- direct space : FOX (free) was the winner of the SDPD
   2002 round robin, DASH (commercial) was the 1998
   winner.

About Rietveld refinements :
GSAS and Fullprof dominate everywhere but in Japan
where RIETAN is apparently preferred. All three software
are available for free.

So, the advice is : use exclusively free software for SDPD.
Yes, they are enough for you.

Nevertheless, for the identification step, you need the ICDD
products and a search-match software, these being very
expensive commercial things...

Best wishes,

Armel



At 13:10 27/09/2006 -0700, you wrote:
>Dear Armel Le Bail,
>
>Firstly, thank you very much for your guide about
>structure solution from XRPD for Young Scientist like
>us. I think SDPD is interesting but it is difficult
>issue I think. Nowadays,
>I am studying about determine lattice parameters and
>space group for new organic or parmacy compounds (but
>just small molecule) so When I searched in internet I
>have finded some softwares such as Fullprof
>(free),Checkcell,Crysfire..etc. I think in my
>studying, first  step is correct peak indexing. I use
>Rigaku X-ray powder diffractometer in research center
>but I have not a software(commercial) yet. This issue
>is very important for me and I want to determine
>lattice parameters and space groups and I want to
>structure solution of these structures from XRPD ( but
>not yet maybe future hopefully) so I have a problem I
>could not decide that how software is the best for me?
>Commercial Programs ( Rigaku Rietveld program- TEXSAN,
>Bruker ­TOPAS..etc.) is essential for me ? or shared
>softwares (like this free fullprof) is enough for me?
>If commercial programs good for me, which programs can
>we buy to our studying?
>I am looking forward to your response and thank you
>very much for your intend.
>
>  Sincerely Yours,
>
>Research Asistant Funda Ozkok (Qualified Chemist)
>Istanbul University
>Advanced Analysis Laboratuary
>Avcýlar, Istanbul / TURKEY



 
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