Re: [sdpd] The (small) budget makes the law

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

Lachlan wrote,

>Why does the sample have to be from a good 1 < grain size < 5 microns
>power - as long as the powder data giving to participants is 
>a representative pattern?  Getting a sample with some crystallites
>in the 10 to 30 micron range would hopefully make it possible
>to perform validation with synchrotron single crystal.

Validation or not validation, both are possible, this is what I
mean. SDPD does not need each time a validation from a
small crystal structure determination, fortunately. SDPD is
self consistent enough when the parameters/N(hkl) ratio is
not too large (should be <10 or 20 in my opinion).

The main prerequisite is that one or two monophasic
samples with unpublished structure have to be selected.
Unpublished but not necessarily unknown, since at least the
organizers must have some proof that the structure determination
is feasible. Good candidates may be some CSD entries without
coordinates (!!), like it was done in the first SDPD Round Robin
for the tetracycline hydrochloride sample. Moreover, such entries
may correspond to compounds sold by chemical companies.

Anyway, if somebody is interested in organizing that 2nd Round
Robin, let him do what he wants (or do it ;-).

Best,

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


-------------------------- eGroups Sponsor -------------------------~-~>
eGroups eLerts
It's Easy. It's Fun. Best of All, it's Free!
http://click.egroups.com/1/9698/14/_/40740/_/972337028/
---------------------------------------------------------------------_->