[sdpd] Re: Ask for reports on ECM19

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

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--- In sdpd...@egroups.com, L.M.D.Cranswick...@d... wrote:

> Given the reputation of EXPO 
> of being very friendly and easy to use - it could be quite a 
> rival to ESPOIR given the setup via Prespoir can be 
> the most tedious part to get going quickly?  (at 
> least when trying to quickly demonstrate the ESPOIR 
> software in showing how to get a new problem working 
> from scratch(?))

Crystallography programs have all in common that tedious part.
They cannot guess the space group, the cell parameters, the
wavelenght, and depending of the program, possibly the starting
atomic coordinates, the starting U, V, W, and what exact option
the user wants to activate. Those parameters have to be
defined with EXPO too, in the .exp file.

If I had to demonstrate how to use Fullprof or GSAS on a
new problem working from scratch, this would need certainly
much more than 10-15 mn, due to the long list of options.
Hard to insert all explanations in a 15-20 mn talk if the
manual has 30-200 pages...

There is another recommended procedure.

The best way to build the datafile is to reuse a previous
one (from examples distributed with the program or from
your own). This supposes that you are already an experienced
user, of course. With experience, the time for building
a datafile considerably reduces, possibly to less than
1 mn. And this time is not very dependent on the presence
or not of an integrated GUI in the program. A modern text
editor is the most marvelous GUI which I know, if compared
to antediluvian text editors (VI and so on).

So, copy an old file which you remember corresponding
to a similar case. Then change only the parameters that
have to be changed. This is the right way. That way is
hardly applicable for a beginner : no GUI can change
the fact that beginners have to get experience, and this
needs time with EXPO or ESPOIR, DIRDIF, PATSEE, etc, etc.

And a last obvious point : as a rule you need even more
time when a program is unavailable or if you cannot
afford it (DASH, OCTOPUS, ROTSEARCH, ENDEAVOUR, Powder
Solve, Hardpack, etc, etc).

Best,

Armel Le Bail
http://www.cristal.org/course/