[Ifeffit] Trouble creating feff input file for NaTiO3 cubic perovskite structure

Dear All, When I try to feed the following data into the atoms input and run the feff calculations, the software just automatically closes. space group no: 221 a = b = c = 3.88; alpha = beta = gamma = 90; atomic coordinates: Na: 0.5, 0.5 , 0.5 Ti: 0, 0, 0 O: 0, 0, 0.5 Core: Ti I don't think it is a bug because the calculation works perfectly when I replace Na with heavier atoms like K, Mg etc. I would like to know why I am not able to create the feff input file using Na. -- Yours Sincerely Badari Narayana. A. R. Ph.D Student, Nanoscience and Nanotechnology, c/o Prof Rajeev Ranjan, Electroceramics Lab, Department of Materials Engineering, Indian Institute of Science.