# compute property/molecule command

## Syntax

    compute ID group-ID property/molecule general_keyword general_values input1 input2 ...

- ID, group-ID are documented in compute command
- property/molecule = style name of this compute command
- general_keywords general_values are documented in compute
- input = one or more attributes

    possible attributes = mol cout
      mol = molecule ID
      count = # of atoms in molecule

## Examples

    compute 1 all property/molecule mol

## Description

Define a computation that stores the specified attributes as global data so it can be accessed by other output commands and used in conjunction with other commands that generate per-molecule data, such as compute com/molecule and compute msd/molecule.

The ordering of per-molecule quantities produced by this compute is consistent with the ordering produced by other compute commands that generate per-molecule datums. Conceptually, them molecule IDs will be in ascending order for any molecule with one or more of its atoms in the specified group.

The mol attribute is the molecule ID. This attribute can be used to produce molecule IDs as labels for per-molecule datums generated by other computes or fixes when they are output to a file, e.g. by the fix ave/time command.

The count attribute is the number of atoms in the molecule.

## Output info

This compute calculates a global vector or global array depending on the number of input values. The length of the vector or number of rows in the array is the number of molecules. If a single input is specified, a global vector is produced. If two or more inputs are specified, a global array is produced where the number of columns = the number of inputs. The vector or array can be accessed by any command that uses global values from a compute as input. See this section for an overview of LIGGGHTS(R)-PUBLIC output options.

The vector or array values will be integers that correspond to the specified attribute.

## Restrictions

> none

Related commands: none

Default: none