Hi Josh, thanks a lot. Yes of course I have the paper and I have read it and that is the reason why I asked the question about what is calculated by IFEFFIT considering the fact that from the mere examination of the numbers I could not make much sense of them. I am writing up a paper and I would like to know well what I am reporting in it.... So I hope Matt will help. Stefano

Hi, I don't know what ifeffit does, but here is a nice paper by Ed Stern which goes through the theory

Number of relevant independent points in x-ray-absorption fine-structure spectra. PRB V. 48 Number 13

The conlcusion is that if you are using r-space data that includes r=0 then

Nidp = 2dkdR/pi + 1

otherwise, when r=0 is not included in the fit

Nidp = 2dkdR/pi + 2

Hope this helps. Josh Kas

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-- ____________________________________________ Stefano Ciurli Professor of Chemistry Laboratory of Bioinorganic Chemistry Department of Agro-Environmental Science and Technology University of Bologna Viale Giuseppe Fanin, 40 I-40127 Bologna Italy Phone: +39-051-209-6204 Fax: +39-051-209-6203 "Fatti non foste a viver come bruti, ma per seguir virtute e canoscenza" Dante Alighieri - Inferno - Canto XXVI "Ihr seid bestimmt, nicht Tieren gleich zu leben, Nein, Tugend zu erringen und Erkenntnis" "Ye were not form'd to live the life of brutes, But virtue to pursue and knowledge high"