[Ifeffit] Questions about fitting of EXAFS

Hi, Everyone, I have several detailed questions about EXAFS processing and fitting 1. Are there any physical meaning for DeltaE0 in the paths, why it should be less than 10eV 2. The cutting range of Kmax (FT transform parameters) has great effect on FTs of EXAFS, how do I know to use the best value of Kmax; 3. How to make refinement equation for multi-scattering paths? Such as in NiFe alloys (simple fcc structure), the path [Ni-FM-3m] Fe1.1 Ni1.4 Fe1.1., I use 0.67*Efe+0.33*Eni for DeltaE0, and 0.67*ssFe1+0.33*ssNi4 for sigma2, is that right? Many thanks Fuxiang Zhang