Follow-up Comment #3, bug #21187 (project relax): The problem is due to a corrupted PDB file. Atom numbers (the second column) must be sequential. The numbers of 0 are invalid according to the PDB standard. I will nevertheless see if there is a solution. If not, I can throw a RelaxError to indicate that this is a fatal PDB corruption - this will be much more informative that the missing 'pos' variable error. _______________________________________________________ Reply to this item at: <http://gna.org/bugs/?21187> _______________________________________________ Message sent via/by Gna! http://gna.org/