From: Axel Kohlmeyer (
Date: Wed May 26 2004 - 15:48:49 CDT

On Wed, 26 May 2004, Randall Hall wrote:

RH> Hello, I have a scalar field (let's call it the electron density)
RH> associated with each frame in a trajectory of a molecule. Is there a way
RH> to read in the field (currently stored in .plt format) for each frame and
RH> then play the trajectory? I can only see a way to read in a single scalar
RH> field and display or read in a bunch of scalar fields and write a tcl
RH> script to only display one field at each step in the trajectory.

it is interesting how often this topic has come up lately.
the latter one is exactly the strategy to use until vmd has some
more advanced support for isosurface animations.
please have a look at


for an example. although this uses cube files, you can load other
volumetric data sets as well. only you have to make sure, that the
data sets are read in the correct sequence corresponding to the
animation. the rest of the script has no dependency on the data format.

good luck,
    axel kohlmeyer.

RH> rwh
RH> Dr. Randall W. Hall
RH> Professor of Chemistry
RH> Louisiana State University
RH> 225-578-3472

Dr. Axel Kohlmeyer                        e-mail:
Lehrstuhl fuer Theoretische Chemie          Phone: ++49 (0)234/32-26673
Ruhr-Universitaet Bochum - NC 03/53         Fax:   ++49 (0)234/32-14045
D-44780 Bochum