Hi Benjamin, You can catalog H-bonds over every frame in a trajectory one frame at a time (there is no need to have all the H-bonds for all frames exist simultaneously). Using the MD Movie tool, just add a per-frame script that runs the “findhbond" command, similar to what’s done in Part 1 of this tutorial: <http://www.rbvi.ucsf.edu/chimera/docs/UsersGuide/tutorials/ensembles2.html> You would include the save-to-file option in that “findhbond” command (if you wanted a separate output for each frame), or use the logging option and then save the Reply Log to file afterwards. This is a common use of Chimera. If you really did need the H-bonds for all frames to exist simultaneously (a reason might be for faster interactive playback of the trajectory with H-bonds), I note that ChimeraX has this capability: See ChimeraX “hbonds” command (“coordsets” option) <http://rbvi.ucsf.edu/chimerax/docs/user/commands/hbonds.html> ChimeraX doesn’t have many tool graphical interfaces yet, but lots of functionality in commands: “open” to open trajectories, “coordset” to play them back (and there is also a relatively simple slider graphical interface): <http://rbvi.ucsf.edu/chimerax/docs/user/commands/open.html> <http://rbvi.ucsf.edu/chimerax/docs/user/commands/coordset.html> The input trajectory formats are more limited, multi-model PDB or mmCIF plus those listed here: <http://rbvi.ucsf.edu/chimerax/docs/user/commands/open.html#trajectory> I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Chimera(X) team Department of Pharmaceutical Chemistry University of California, San Francisco

On May 19, 2018, at 11:48 AM, benjamin.horsman@alumni.ubc.ca wrote:

Hello, A 2014 message to chimera-users mentioned that "There is also a hidden capability in Chimera to compute all bonds on a per-frame basis." (http://plato.cgl.ucsf.edu/pipermail/chimera-users/2014-April/009759.html)

Could someone please elaborate on this? Does this functionality still exist is recent versions of Chimera, and has it been documented anywhere?

My requirements are just that - to catalogue all (hydrogen) bonds over every frame in a trajectory. Thank you, BGSH