visualizing stress field

Hello,

I want to calculate and plot the stress field for a system with an initial knock.

I have calculated the stress/atom for each timestep using the “stress/atom” command in LAMMPS.

It is not very clear to me how can I plot the stress field and make a movie to show the change of stress field with time.

I tried to visualize with VMD and could not do that.

I am sorry to pose a question which may not be very much related to the technical difficulty with the usage of LAMMPS.

But it will be a great help, if someone can give a hint to visualize the stress field using the LAMMPS dump file.

Best regards,

Hello,

I want to calculate and plot the stress field for a system with an initial
knock.

I have calculated the stress/atom for each timestep using the "stress/atom"
command in LAMMPS.

It is not very clear to me how can I plot the stress field and make a movie
to show the change of stress field with time.

neither to me. how do you *want* to represent a
tensorial property at the location of an atom?

I tried to visualize with VMD and could not do that.

how can something work, if you don't know what you
can show it the first place? how would you convey the
stress information to VMD and what should it do with
it after you have done that.

I am sorry to pose a question which may not be very much related to the
technical difficulty with the usage of LAMMPS.

But it will be a great help, if someone can give a hint to visualize the
stress field using the LAMMPS dump file.

any hint would depend on your answer to the question
of how you would want to visually represent a tensor.

axel.

You mean stress field as “stress strain curve” or you mean “the pressure of the entire system of atoms” . You can use the “compute pressure command” or “stress/atom” as you suggest: This compute calculates a global scalar (the pressure) and a global vector of length 6 (pressure tensor), which can be accessed by indices 1-6. These values can be used by any command that uses global scalar or vector values from a compute as input.

I would suggest to dump the atomic configuration as “cfg” and visualise the frames using “atomeye” (since its compatible with lammps).

example :

compute 1 mobile stress/atom
dump 2 all cfg 10 dump.snap.*.cfg id type xs ys zs vx vy vz c_mobile[1] c_mobile[2] …c_mobile[6]

hope this help
Oscar Guerrero

I find it hard to believe that VMD does not support that.
Anyhow a nice visualization package that is geared more towards
materials science is Ovito.
Check it out at http://www.ovito.org/ (it imports lammps dump files
and can use arbitrary colums and expressions to color atoms)
Of course it is up to you how you use that functionality to visualize
a 6dimensional vector (or rather tensor)