Hi Tammy,
There is a brief mention of simultaneous X-ray neutron refinements in Young's
Book "The Rietveld Method". GSAS and a few other packages can do this (can
FullProf?). There are 2 main problems on a simplistic level. Firstly, X-rays
see the electron density and neutrons the nucleus. This
For simultaneous single-crystal X-ray and powder neutron diffraction
refinements (with split H atoms!) see for example:
Chem.Comm. 1997, 1903.
Regards
Norberto
---
Norberto Masciocchi
Dipartimento di Chimica Strutturale e Stereochimic
OK to follow up Andrew's remarks:
I use simultanous X-ray and neutron refinements almost all the time
nowadays. There are a lot of advantages when you like me work with
transition metal oxides:
1) in general the refinement is more stable.
2) the possibility the study much more complicated str
(A warning that unhealthy amounts of self citation follow)
For a possible pitfall where the X-ray and Neutrons can be telling
you different information - and thus combined X-ray/Neutron refinement
can average out some interesting structural information, refer:
"Structure analysis of the 6H-Ba(
Hi Tammy,
In answer to your first question, when you start EXPEDT enter 'Y L L P'. This
takes you to the listing control menu. Enter 'C' to print the correlation
matrix. The output from a GENLES cycle is to the .LST file. All I know about
the .CMT file is that it is a binary file created by GSAS
Jaap wrote :
>Reactions?
yes ! How many time between the synthesis, the X-ray
pattern refinement and then the refinement of both neutron
and X-ray patterns ?
Suppose that you synthesize your sample today. you may have
a good X-ray pattern in less than a month, probably. Then
the neutron pattern
The point made by Armel is possibly misplaced.
Whilst I agree that waiting for neutron data does impose a considerable
delay when compared against readily available laboratory X-ray facilities,
this misses the point somewhat. In the cases Jaap outlined an X-ray
diffraction experiment would be
I also use combined CW neutron and synchrotron refinements. A simple
minded justification goes as follows. Most of the problems I work on are
badly underdetermined -- at least by the crystallographic rule-of-ten
(10 crystallographic observations for each structural variable). By
changing scatterin
Brian wrote:
>Finally, I should mention in response to Armel that at least here at
>NIST, most requests for time are scheduled within 2-8 weeks of when we
>get them (see http://www.ncnr.nist.gov/~toby/bt1.html).
The confirmation of what I suspected : some peoples are
more equal than others !-)
