Hi Marcus,

From the graph, it looks likely that one of your sigma2’s is negative, causing the fit to blow up at high k.

If so, then the apparently good fit below k=9 is actually a “false fit,” meaning that it looks good on a graph, but is nonphysical. Unfortunately, that means you have more work to do in adjusting the model; you shouldn't just narrow the fitting window and ignore the misfit. Best, Scott Calvin Lehman College of the City University of New York

On Jan 17, 2017, at 4:21 AM, mfehse wrote:

Dear all,

im fitting Ti next neighbour environment and I'm facing the problem that above a k value of 9 the fit deviates completely and does not follow the data any more. I dont really understand what is happening, so im forced to limit my fitting window in order to avoid this effect. i have attached a plot in k space so you can better understand what im talking about.

any hints would be appreciated_______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit