[Chimera-users] Hbond analysis in trajectories

Elaine Meng meng at cgl.ucsf.edu
Tue Dec 20 14:35:34 PST 2011

Hi George, 
You would need to define a per-frame script in MD Movie that includes the findhbond command.  First just use the regular command line and the manual page to figure out what command options you need.

>From what you said it would probably include "selRestrict any" and "log true" (send to Reply Log instead of file... then at the end you can save the Reply Log contents to a file).

Once you know the proper command, then enter it as a per-frame script in MD Movie.  From the MD Movie menu, choose Per-Frame... Define script. Enter the hbond command as a script to be interpreted as Chimera commands.  Then you would probably want to clear the Reply Log (under Favorites in the menu, has a "Clear" button on it), turn off looping in MD Movie, and just play from start of trajectory to end to save all the H-bond info into the log.  Then use the Save button on the Reply Log to save to file.

There is a similar per-frame script example in the "Trajectories/Ensembles" tutorial, part 1:

Besides saving everything to the log, another possibility is to make the script write a separate output file for each step, if that is more convenient for you.

I hope this helps,
Elaine C. Meng, Ph.D. 
UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab
Department of Pharmaceutical Chemistry
University of California, San Francisco

On Dec 20, 2011, at 11:29 AM, George Tzotzos wrote:

> I'm trying to analyse Hbond formation during a 2ns AMBER trajectory involving receptor ligand complex. The trajectory loads as expected. I've selected the ligand and I checked the boxes "Only find H-bonds with at lease one end selected" and "Write information to file" .
> The output hbond.info contains information of a single frame.
> My question is whether there's a way by means of which information of ALL frames can be printed out.
> Many thanks and best regards
> George

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