Dear all, Following the previous discussion ( https://www.mail-archive.com/ifeffit@millenia.cars.aps.anl.gov/msg07118.html ) on using more than one CIF file for fitting, as Scott Calvin and Matthew Marcus suggested, we can fold the molar ratio into the amp parameter for each CIF. Does it mean that the overall S02 for all phases (all used CIF files in the fitting) is "set" to 1? Typically, for the regular fitting with one model (cif file or any simulated feff file), we take the S02 value from the known metal foil that has been measured simultaneously with the unknown sample. So if we used the mentioned method and folded the molar ratio into the amp, does it mean in Artemis we use the following terms? "in Artemis: S02= abs(amp) for one phase and for another one: S02= abs(1-abs(amp)" and leave “amp” parameter to “guess” Also if we are using X, Y, Z,.... CIF files, does it mean the summation of all S02 for all X,Y,Z,... cif models would be equal to 1? Im not sure, but I guess in this work ( https://www.sciencedirect.com/science/article/pii/S0016703702008888 ), the authors used this way and fixed the overall S02 for all phases to 1. I would appreciate having your comment on this method or if you have any suggestion on how to deal with the S02 value in Artemis when we are using more than 2 or 3 phases (cif files) for the fitting process. Thank you in advance, Bests, Esmael -- Linkedin: www.linkedin.com/in/esmael-balaghi https://www.linkedin.com/in/esmael-balaghi/i