Ciao Bruce, here are all files necessary to reconstruct the problem. I do the following: - open a data file - open a feff calculation - set all fitting parameters (window, kmin, kmax, etc) - include the first path and set the nr. of neighbours to 4 - fit it, keep s02 fixed to 0.82, the other parameters vary => 3 Variables. until here everything is fine. then I do: - add the 2nd path, set the nr. of atoms in path0001 to 1 and path0002 to 3 - insert the corresponding GUESSes - fit it. as i set the same e0 and keep s02 fixed, it should be 5 variables now, but artemis reports 3 :) when i redo the same fit, it reports the correct value. This behaviour seems to be uniform because I tested it with 3 datafiles already. Hope that helps to track the problem down. Cheers, Norbert -- Dr. rer. nat. Norbert Weiher (norbertweiher@yahoo.de) Institute for Chemical and Bioengineering - ETH Hönggerberg HCI E 117 - 8093 Zürich - Phone: +41 1 63 3 48 32