From: Axel Kohlmeyer (
Date: Sat Mar 05 2011 - 12:27:23 CST

dear alberto,

On Fri, Mar 4, 2011 at 10:35 AM, alberto baldelli <> wrote:
> Hi,
> I am Alberto, a Phd candidate at the Indiana University of Pennsylvania. I
> am working with lammps an visualizing my simulations with Xmovie, but now I
> am trying to use VMD, because more efficient. I would like to display not
> only the positions, but also the velocities, forces and temperatures of my
> lattice, created with lammps.

> Does anyone know an easy way to do so? It will be so nice for my work.

easy? probably not. also, how would you want to visualize
"temperature" which is an ensemble property and not at all
stored in LAMMPS trajectory files?

the current plugin API does allow importing velocities and
the latest reader for lammps trajectories (as distributed with
current VMD 1.9beta versions) has read support for them
implemented. other properties currently have to be imported
using a hack that requires setting an environment variable,
LAMMPSREMAPFIELDS. this allows to override supported
fields, like x, y, z, vx, vy, vz with any other field. e.g. to read
forces instead of velocities you'd use:
and so on.
alternately, you can write a reader for lammps dumps in Tcl
yourself and use VMD scripting to assign any property you
want to, say, user, user2, user3, or user4. this situation will
improve in the future, but for the time being this is all you can do.

as to how to visualize, you have to be creative. you can e.g.
use coloring by velocity or will have to use custom scripts
with callbacks that hook into the vmd_frame variable.
for details, see the VMD user's guide, tutorials and example scripts.


> Thank so much,
> Alberto.

Dr. Axel Kohlmeyer
Institute for Computational Molecular Science
Temple University, Philadelphia PA, USA.