Marco,
On Mon, Sep 7, 2015 at 9:53 PM, M.F.Bertuzzo
Dear all,
I am facing this error when I try to run a fit. The file in question required a larger than normal Rbkg value of 3.0.
In what sense did this **require** Rbkg > 3.0? Normally (and for your data as well), Rbkg around 1.0 is sufficient. Well, if you want to analyze the first shell, that is. Your example nicely demonstrates how Rbkg > first shell distance can remove the first shell from the EXAFS... if that's what you want.
I have attatched the Athena file & the subsequent Artemis project file that I tried to fit so you can see the error I am facing.
From what I can understand, I need to reduce the Rbkg value in the Athena file to a lower number. But whenever I try to do this it causes the background function to mess up which then also causes problems for the fit in 'R' space.
Well, it needs to be a lower number if you want to analyze the first shell, because with Rbkg=3, you've mostly removed the first shell from your data.
Is this problem because I have badly modeled the data badly in Athena to begin?
I'm not really sure how to solve the problem so your help and advice is much appreciated!
For your data, I'd recommend trying kweight=2 in the background subtraction, and perhaps moving e0 up a little bit. You could try a "clamp" on the **high k** side, too. Be aware that you're not going to analyze the data below 2 Ang^-1 anyway, so that if the background looks like it's way to high at very low k, this is not actually a problem. Hope that helps, --Matt