[Chimera-users] Visualizing trajectory

Elaine Meng meng at cgl.ucsf.edu
Fri Mar 7 14:46:19 PST 2014

Hi Yasser,
(1) Yes, you can specify atoms to be held steady as possible in the view.  After loading your trajectory, you can select some atoms (for example, command "select protein" for all protein atoms or "select @CA" for all alpha-carbons) and then choose from the MD Movie menu: Actions... Hold Selection Steady.  Then you can un-select the atoms and play the trajectory.  It will remember which atoms you had selected when you chose that menu item, and try to keep those from moving around.  See the MD Movie manpage:

(2) You can load the trajectory partly by specifying starting and ending frame, but I don't know of any way to load only every Nth frame.  You can play back only every Nth frame, but that's after every one in the specified start-end range is loaded.  As far as I know, if somebody wants to only load every Nth frame, they would have to use some other processing program or script to create a new trajectory that only contains those frames.

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 Mar 7, 2014, at 2:17 PM, Yasser Almeida Hernández wrote:

> Hi all,
> I have a MD trajectory from GROMACS and I want to visualize it in
> Chimera using MD Movie tool.
> My protein move inside the water box. How I cant fix the protein to see
> the its dynamics in each frame?
> I have used VMD for this task, using the RMSD trajectory calculator
> plugin. Here the trajectory is loaded and then press the Align button.
> The protein coordinates in each frame is superposed on those from the
> first frame. Whith this the protein stay in a fixed position.
> It is this possible in Chimera?
> On the other hand, It is possible load the trajectory just by every N
> frames? I have a trajectory with 2 000 000 of frames, and I want to load
> the trajectory every 100 frames.
> Thanks in advance
> Yasser

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