Use LAMMPS as post processing tool

Ciao. I'm wandering if there is some way to use LAMMPS
as a post processing tool to analyse already computed
LAMMPS trajectories in a previous run.

The fact is I often find myself in need of refine some
simulation aspects or observables of an already performed
simulation, for example restricting some "computes"
to some subdomain or subgroup, or adding new ones.

Running the simulation again with new computes and/or
new groups is a very waste of time and power, since all
information for many computes (most of the time)
is already present in, say, lammpstrj files
(or whatever used to dump pos and vel).

I know there are many post processing tools and python
scripts for that (such as PIZZA-python and those in tools/),
but the powerful features of defining groups, regions
and restricting computes to them are already implemented
in LAMMPS!

luca ferraro

ciao luca,

Ciao. I'm wandering if there is some way to use LAMMPS
as a post processing tool to analyse already computed
LAMMPS trajectories in a previous run.

not yet, but is on my TODO list. we've had discussions
on the subject a few times on the list and i have since
received code from tim sirk to read a single frame
from a lammps dump (is in LAMMPS-ICMS, in case
anybody is interested).

i expect to have some time for programming projects
over the summer and one of the things i want to look into
is to interface lammps to the VMD molfile plugin library
(for read and write) and then have a run style rerun that
would do exactly what you are describing for exactly
the reasons that you are describing (and then some).

cheers,
    axel.

we are working (slowly) on a "rerun" command
that would allow reading of snapshots from a dump
file and the options you mention.

Steve