Dear Feff community, I have a question concerning the position of the absorbing atom when creating a feff input file. I am trying to calculate the EXAFS for a disk-like Ru nanoparticle that I "built" from literature data using the program Diamond. The particle has 3 atomic layers, looks somewhat half-pyramidal and consists of about 80 atoms. I then exported the atom positions and used them as an input for feff. Since my cluster is far from being a bulk structure, the spectrum I get strongly depends on where I place my absorbing atom. In this cluster the atoms can be grouped by common coordination number. Do I have to manually calculate the EXAFS for every single group and then calculate the mean spectrum weighted with the degeneracy of each group or is there a smarter way to do that? Many thanks, Marian. Marian Dreher, Dipl. Chem. PhD Student, Catalytic Process Engineering Group Paul Scherrer Institut General Energy Research (ENE) Laboratory for Bioenergy and Catalysis Office: OVGA/115 CH-5232 Villigen PSI Switzerland Phone: +41 (0)56 310 2937 email: marian.dreher@psi.ch