Dear collegues,
my name is Tadej Rojac and I'm writing from the
Institute Jozef Stefan in Ljubljana, Slovenia. I work in the Department of
electronic ceramics. Actually, I'm working on a EXAFS spectra with Artemis.
What I am trying to do is mainly to describe an EXAFS spectrum with a model
concerning the structure of Nb2O5. I'm working togheter with prof. Iztok
Arcon, who is a specialist in the field. My main problem is that I have to do
some suppositions. In fact Nb2O5 structure is quite complicated. It is
composed of seven different Nb positions which I took into account using 7
feffs in Artemis. I don't know the exact occupancies of the seven
positions. In order to make the search easier I did at first
a supposition that all the occupancies must be positive, which is
realistic. I set this with the command "abs" in each feff file. Secondly,
I need to supose that the sum of all occupancies is 1. In that way the
search for the result is much easier, otherwise I get the sum greater than
one, which, for sure, is not the case. My question is how can I do that? For
example, if the occupancies are O1, O2, O3, O4, O5, O6 and O7 and I define
them with a starting value (let use say the same, so 1/7) than I can do O =
O1+O2+O3+O4+O5+O6+O7. Finally I need to do O =1, but here Artemis doesn't
want to define the same parameter (O in this case) twice. So, how can I insert
the conditions, that the sum of all the occupancies is 1, into Artemis? I
hope you can help me.
I'm looking forward t hearing from you...thank
you...
Tadej Rojac
Jozef Stefan Institute
Jamova
39
1000 Ljubljana
Slovenia
Tel.: +386 1 477 38 34
Fax: +386 1 477
38 87
E-mail: tadej.rojac@ijs.si