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. See Section 2.6 for an explanation of the 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.