Hello Matt and Tsu-Chien, I am using MacOSX, and editing the file either using vi or textedit. While trying to ignore the error I was getting (I also thought initially it was a problem with format of line ending, but I excluded it) I used the file that Tsu sent to me (Hoping it was a sort of jinx I was going through...). Running the file as received, I got the following error: Feff 6L.02 Fatal Error: No absorbing atom (ipot=0) defined So I modified the distances and coordinates, thinking that, for some obscure reason that was the problem, but I get exactly the same error message. There must be a matter of invisible wrong spacing. I attach the file I am using. Looking forward to hearing from you. Stefano -- ____________________________________________ Stefano Ciurli Professor of Chemistry Department of Agro-Environmental Science and Technology University of Bologna Viale Giuseppe Fanin, 40 I-40127 Bologna Italy Phone: +39-051-209-6204 Fax: +39-051-209-6203 "Fatti non foste a viver come bruti, ma per seguir virtute e canoscenza" Dante Alighieri - Inferno - Canto XXVI