VMD-L Mailing List

From: Axel Kohlmeyer (akohlmey_at_gmail.com)
Date: Fri Jan 01 2010 - 10:16:38 CST

2010/1/1 <wenchangyu2006_at_gmail.com>:
> Thank you, axel. Actually the picture on the webiste is exactly the one I
> want to make. I searched the user guide about "inertia tensor" measurement
> and I think I know how to draw a line in VMD. But I really don't know how to
> transfer the information from inertia to draw the line. I think there should

all you need is a little bit of spatial geometry and imagination
and then write a bit of tcl script.

you can use the measure inertia command to get the vector of the largest
moment of inertia for the corresponding selection of atoms in your system,
and the center of mass. from the center of mass and that vector you can
easily compute the endpoints of the lines by adding or subtracting
the vector times a scaling factor from the center of mass. now add a loop
around this that steps through a few time steps and change the color at
every step before you draw the line and you are done. piece of cake.

> be someone in UIUC made the picture when they put the picture on the
> website. Thank you for any suggestion.

the image looks as if it was done with a fairly old version of VMD, so i would
assume that the chances that the person who created that image is still at
the TCBG is quite low. with the effort we spent just figuring out what you
really want, you could have already written that kind of visualization script.

cheers,
   axel.

>
> Best,
> wenchang 

-- 
Dr. Axel Kohlmeyer    akohlmey_at_gmail.com
Institute for Computational Molecular Science
College of Science and Technology
Temple University, Philadelphia PA, USA.