compute pair/local command

Syntax:

compute ID group-ID pair/local input1 input2 ... 

• ID, group-ID are documented in compute command
• pair/local = style name of this compute command
• zero or more keywords may be appended
• keyword = dist or eng or force

    dist = tabulate pairwise distances
    eng = tablutate pairwise energies
    force = tablutate pairwise forces 
  

Examples:

compute 1 all pair/local eng
compute 1 all pair/local dist eng force 

Description:

Define a computation that calculates properties of individual pairwise interactions. The number of datums generated, aggregated across all processors, equals the number of pairwise interactions in the system.

The local data stored by this command is generated by looping over the pairwise neighbor list. Info about an individual pairwise interaction will only be included if both atoms in the pair are in the specified compute group, and if the current pairwise distance is less than the force cutoff distance for that interaction, as defined by the pair_style and pair_coeff commands.

The output dist will be in distance units. The output eng will be in energy units. The output force will be in force units.

Note that as atoms migrate from processor to processor, there will be no consistent ordering of the entries within the local vector or array from one timestep to the next. The only consistency that is guaranteed is that the ordering on a particular timestep will be the same for local vectors or arrays generated by other compute commands. For example, pair output from the compute property/local command can be combined with data from this command and output by the dump local command in a consistent way.

Output info:

This compute calculates a local vector or local array depending on the number of keywords. The length of the vector or number of rows in the array is the number of pairs. If a single keyword is specified, a local vector is produced. If two or more keywords are specified, a local array is produced where the number of columns = the number of keywords. The vector or array can be accessed by any command that uses local values from a compute as input. See this section for an overview of LAMMPS output options.

The output for dist will be in distance units. The output for eng will be in energy units. The output for force will be in force units.

Restrictions: none

Related commands:

dump local, compute property/local

Default: none