Bruce: I have recently encountered a weird problem with TkAtoms. Let me detail it setp by step. 1. Start TkAtoms and build a model from scratch. 2. Press the "Run Atoms" button. The output of this is correct and can be saved to disk. 3. Save the "atoms.inp" file associated with the model that has been successfully run and exit TkAtoms. 4. Start TkAtoms again and load the previous "atoms.inp" file. 5. Press the "Run Atoms" button again. This time the output (the FEFF input file) is completely different than in step 2. It is also completely incorrect. Many of the x,y,z coordinates are set to zero. In fact the x coordinate is always zero. If I clear the data boxes and re-enter the original numbers, the results are correct once again. This is extremely confusing to me. I have only tried it with a single structure but it shows this behavior consistently. I have attached the offending atoms.inp file. Carlo -- Carlo U. Segre -- Professor of Physics Associate Dean for Research, Armour College Illinois Institute of Technology Voice: 312.567.3498 Fax: 312.567.3494 Carlo.Segre@iit.edu http://www.iit.edu/~segre