[Ifeffit] protonated pentatitanate

[Dominik Samuelis]

Dear Marie,

if you have five crystallographically non-equivalent Ti-atoms, you need 
to do feff calculations for each of the five atoms as core. The final 
model then is the sum of these five calculations, each multiplied by the 
multiplicity and the occupancy of it's core site.

This sounds more complicated than it really is. If you load more than 
one FEFF calculation into Artemis, it'll automatically sum over all 
path. The only thing that you need to do is to define the amp values of 
each calculation in a way like:

[def] <amp_1> := 1/N_Ti*<multiplicity_1>*<occupancy_1>*global_amp
[def] <amp_2> := 1/N_Ti*<multiplicity_2>*<occupancy_2>*global_amp
...

global_amp needs to be introduced as a new guess parameter. This value 
then holds the S02 value for the whole system.

In your case, both multiplicity and occupancy for each core are 1, N_Ti 
(the total number of Ti atoms) is 5.


Cheers,
dominik

A M wrote:
> Dear All
> 
> I have huge problem with my spectra for protonated pentatitanate ( H_2 
> Ti_5 O_11 *3H_2 O), I’ve tried to build theoretical model for this 
> compound (penta.cif) but unfortunately I have 5 Ti atoms in my formula, 
> so I really don’t know what Ti I should select as a core atom...I tried 
> with 5 different options Ti1....Ti5, so I obtained 5 different models 
> (with distances between Ti-O in first shell sometimes very short 1.59A)...
> 
> I would be very grateful for any help....
> 
> Best regards
> Marie
> 
> 
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-- 
Dr. Dominik Samuelis
d.samuelis at fkf.mpg.de
Max-Planck-Institut für Festkörperforschung
Max Planck Institute for Solid State Research
Heisenbergstr. 1
70569 Stuttgart
Germany
Phone +49-711-689-1769
Fax   +49-711-689-1722
Web   http://www.fkf.mpg.de/maier/