partition command


partition style N command ...
  • style = yes or no
  • N = partition number (see asterisk form below)
  • command = any LAMMPS command


partition yes 1 processors 4 10 6
partition no 5 print "Active partition"
partition yes *5 fix all nve
partition yes 6* fix all nvt temp 1.0 1.0 0.1


This command invokes the specified command on a subset of the partitions of processors you have defined via the -partition command-line switch.

Normally, every input script command in your script is invoked by every partition. This behavior can be modified by defining world- or universe-style variables that have different values for each partition. This mechanism can be used to cause your script to jump to different input script files on different partitions, if such a variable is used in a jump command.

The “partition” command is another mechanism for having as input script operate differently on different partitions. It is basically a prefix on any LAMMPS command. The command will only be invoked on the partition(s) specified by the style and N arguments.

If the style is yes, the command will be invoked on any partition which matches the N argument. If the style is no the command will be invoked on all the partitions which do not match the Np argument.

Partitions are numbered from 1 to Np, where Np is the number of partitions specified by the -partition command-line switch.

N can be specified in one of two ways. An explicit numeric value can be used, as in the 1st example above. Or a wild-card asterisk can be used to span a range of partition numbers. This takes the form “*” or “*n” or “n*” or “m*n”. An asterisk with no numeric values means all partitions from 1 to Np. A leading asterisk means all partitions from 1 to n (inclusive). A trailing asterisk means all partitions from n to Np (inclusive). A middle asterisk means all partitions from m to n (inclusive).

This command can be useful for the “run_style verlet/split” command which imposed requirements on how the processors command lays out a 3d grid of processors in each of 2 partitions.