[Ifeffit] XANES from FEFF9

Matt Newville newville at cars.uchicago.edu
Sun Jul 15 17:29:09 CDT 2018


Hi Manju,

On Fri, Jul 13, 2018 at 11:55 PM manju rao <manju.rao007 at gmail.com> wrote:

> Hi Matt
>
> As I am new to FEFF, I was estimating SO2 to be equal to 1 for XANES. But
> I don't know if it was good to have such guess or not.
>

​OK. Just be be clear, using S02=0 will tell Feff to *not* set S02 to 1,
and that will alter the result.
​

>
> By changing Exchange card from 0 0 0 0 to 0 0 0 2, I am getting a
> noticeable change in absorption edge.


​OK, that's good.   Using a ground state potential should give different
results from using the Hedin-Lundquist model.

Were you expecting to change this parameter and get no change in output?

​

> The edge showed a little shift to higher energy and also slight fall in
> amplitude of edge. These changes are not ignorable. So I am confused about
> what approach to follow.
>

​There are a number of parameters​ for Feff9, and changing these does
typically alter the result -- it's more or less why they exist.

Sorry if this sounds curt of impolite, but I don't understand what you are
expecting to happen.

What are you hoping to get out of these calculations?

--Matt
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