question about lammps

I have not tried using the "lammps-daily" ubuntu package. I'm curious
to know what happens when you run:

mpirun -np 1 lammps-daily

?
If it says "mpirun: command not found", then try this:

sudo apt-get install mpi-default-bin mpi-default-dev

and try running "mpirun -np 1 lammps-daily" again.
(Also, if it says this, then please email us back. mpi-default-bin
should be a required dependency for lammps-daily.)

Otherwise, I would not worry.

     I think that warning message just means that this version of
LAMMPS was compiled with the optional USER-OMP package included, which
enables support for OpenMP (in addition to MPI). I don't think it's a
problem at all. Either way, if you want to run LAMMPS in parallel,
you would precede whatever command you normally use to invoke LAMMPS
with "mpirun". Typically you would preceed it with "mpirun -np N",
where "N" is the number of CPU cores you want to utilize. (It gets
fancier than that, but start with that.)

     And if you want to take advantage of OpenMP, read this link:

http://lammps.sandia.gov/doc/accelerate_omp.html

On that page there are some examples of how to run your simulation in
parallel either using pure OpenMP, or a combination of MPI and OpenMP.

Cheers
Andrew

P.S.
If you want to, you can customize how the work is divided between CPU
cores using these commands:

http://lammps.sandia.gov/doc/balance.html
http://lammps.sandia.gov/doc/fix_balance.html
http://lammps.sandia.gov/doc/processors.html
http://lammps.sandia.gov/doc/partition.html

If you plan to try using GPUs, take a look at:

http://lammps.sandia.gov/doc/Section_accelerate.html

If the warning message annoys you, you can set the OMP_NUM_THREADS
variable (or any environment variable) using a bash command like this

export OMP_NUM_THREADS="1"

(It looks like unless you invoke LAMMPS with the "-sf omp" argument,
the OMP_NUM_THREADS variable will be ignored.)

https://wiki.archlinux.org/index.php/Environment_variables
https://www.digitalocean.com/community/tutorials/how-to-read-and-set-environmental-and-shell-variables-on-a-linux-vps