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# compute smd/contact/radius command

## Syntax

    compute ID group-ID smd/contact/radius

- ID, group-ID are documented in compute command

- smd/contact/radius = style name of this compute command

## Examples

    compute 1 all smd/contact/radius

## Description

Define a computation which outputs the contact radius, i.e., the radius used to prevent particles from penetrating each other. The contact radius is used only to prevent particles belonging to different physical bodies from penetrating each other. It is used by the contact pair styles, e.g., smd/hertz and smd/tri_surface.

See this PDF guide to using Smooth Mach Dynamics in LAMMPS.

The value of the contact radius will be 0.0 for particles not in the specified compute group.

## Output info

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

The per-particle vector values will be in distance units.

## Restrictions

This compute is part of the MACHDYN package. It is only enabled if LAMMPS was built with that package. See the Build package page for more info.

## Related commands

dump custom smd/hertz smd/tri_surface

## Default

none