Hi, Apparently Chimera insists on consecutive serial atom numbers (the first column after ATOM in the pdb file) when it reads in castp files. If that's not the case (as most often happens when hydrogens are attached during the refinement run but are not written out to the final pdb) Chimera complains about incompatibility between the mouth file and coordinates and refuses to read in the castp files. This is my first encounter with a program that cares about the atom number column but I learnt it the hard way. Cheers, Boaz Boaz Shaanan, Ph.D. Dept. of Life Sciences Ben-Gurion University of the Negev Beer-Sheva 84105 Israel E-mail: bshaanan@bgu.ac.il Phone: 972-8-647-2220 Skype: boaz.shaanan Fax: 972-8-647-2992 or 972-8-646-1710