[Ifeffit] convergence of XANES for STO

[Matthew Marcus]

How did you pick the values of the various parameters in the feff.inp file such as Vr, Vi and the SCF parameters?
I once tried to do the Zn edge of ZnO and didn't come close, then gave up because there were too many parameters
to play with.
    mam
----- Original Message ----- 
From: "Lena Fitting" <lf56 at cornell.edu>
To: <fwang at phys.ualberta.ca>; "XAFS Analysis using Ifeffit" <ifeffit at millenia.cars.aps.anl.gov>
Sent: Monday, June 18, 2007 8:49 AM
Subject: Re: [Ifeffit] convergence of XANES for STO


Hi Feng,

Thanks for your reply.
I've already tried to increase the broadening, but that results in
spectra with a resolution worse than that of the experimental results.

Regards,
Lena


Feng Wang wrote:
> Hi Lena,
>
> It is no suprising to see the change of the fine structure near the edge
> within a cluster of that size, because of the long mean free path of the
> photoelectron.
>
> You used a broadening of 0.2eV in your FEFF input, which should give you
> more details than your experiments.
>
> Good luck,
>
> Feng
>
>
>
>> Dear all,
>>
>> I have a question regarding the convergence of XANES calculations. I'm
>> currently focusing on the O-K edge of perovskite oxides, in particular
>> SrTiO3 and found that there are still fine-structure changes for large
>> (9.5Å) clusters. Attached is my *.inp file for the 9.5Å cluster and a
>> summary of the XANES for increasing cluster sizes from 6.5Å to 9.5Å. You
>> can see that there are still significant changes as the cluster size is
>> increased from 8.5 to 9.5Å. In particular, I find a double peak feature
>> in the first 5eV after the edge onset, which is not observed
>> experimentally. Do you have any suggestions how to obtain a better
>> convergence?
>>
>> Secondly, if you compare the simulated XANES with experimental results
>> (see attachment: EELS STO.png), I'm not able to match all three main
>> peaks, even by scaling the energy scale. Are the deviations I'm seeing
>> within the accuracy of FEFF or do I need to improve my *.inp file?
>>
>> Best regards,
>> Lena
>>
>> ---------------------------------
>> Lena Fitting Kourkoutis
>> E13 Clark Hall
>> Cornell University
>> Applied and Engineering Physics
>> Ithaca, NY 14853
>>
>> phone: 607-255-0654
>> e-mail: lf56 at cornell.edu
>> ---------------------------------
>>
>
>
>
> ====================================
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> 11421 Saskatachewan Drive
> Edmonton, Canada T6G 2M9
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-- 
---------------------------------
Lena Fitting Kourkoutis
E13 Clark Hall
Cornell University
Applied and Engineering Physics
Ithaca, NY 14853

phone: 607-255-0654
e-mail: lf56 at cornell.edu
---------------------------------


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