Hello Chimera team, I recently conducted a MD simulation of a 12-mer peptide adjacent to a hydroxyapatite crystal using NAMD 2.6. When I viewed the output coordinates from the simulation in pdb format using Chimera 1.4, the protein ribbon was broken and the hydrogens of certain residues were not bonded but in close proximity. All of the non-bonded hydrogens were colored purple by default. The waters of the system and the crystal looked normal. Overall, the protein looked distorted. I decided to visualize the peptide using VMD 1.8.7 and to my surprise the protein ribbon was intact with all hydrogens bonded to their respective residues. Any insight into why this difference occurred would be greatly appreciated. Best, Keith Battle Research Technician University of South Alabama