"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c

:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Section_commands.html#comm)

:line

processors command :h3

[Syntax:]

processors Px Py Pz :pre

Px,Py,Pz = # of processors in each dimension of a 3d grid :ul

[Examples:]

processors 2 4 4 :pre

[Description:]

Specify how processors are mapped as a 3d logical grid to the global
simulation box.

When this command has not been specified, LAMMPS will choose Px, Py,
Pz based on the dimensions of the global simulation box so as to
minimize the surface/volume ratio of each processor's sub-domain.

Since LAMMPS does not load-balance by changing the grid of 3d
processors on-the-fly, this command should be used to override the
LAMMPS default if it is known to be sub-optimal for a particular
problem.  For example, a problem where the atom's extent will change
dramatically over the course of the simulation.

The product of Px, Py, Pz must equal P, the total # of processors
LAMMPS is running on.  If multiple partitions are being used then P is
the number of processors in this partition; see "this
section"_Section_start.html#2_6 for an explanation of the -partition
command-line switch.

If P is large and prime, a grid such as 1 x P x 1 will be required,
which may incur extra communication costs.

[Restrictions:]

This command cannot be used after the simulation box is defined by a
"read_data"_read_data.html or "create_box"_create_box.html command.
It can be used before a restart file is read to change the 3d
processor grid from what is specified in the restart file.

[Related commands:] none

[Default:]

LAMMPS chooses Px, Py, Pz
