# compute contact/atom command

## Syntax

compute ID group-ID contact/atom

• ID, group-ID are documented in compute command

• contact/atom = style name of this compute command

## Examples

compute 1 all contact/atom


## Description

Define a computation that calculates the number of contacts for each atom in a group.

The contact number is defined for finite-size spherical particles as the number of neighbor atoms which overlap the central particle, meaning that their distance of separation is less than or equal to the sum of the radii of the two particles.

The value of the contact number will be 0.0 for atoms not in the specified compute group.

Output info:

This compute calculates a per-atom vector, whose values can be accessed by any command that uses per-atom values from a compute as input. See the Howto output doc page for an overview of LAMMPS output options.

The per-atom vector values will be a number >= 0.0, as explained above.

## Restrictions

This compute requires that atoms store a radius as defined by the atom_style sphere command.