# fix planeforce command

## Syntax

    fix ID group-ID planeforce x y z

-   ID, group-ID are documented in [fix](fix) command
-   planeforce = style name of this fix command
-   x y z = 3-vector that is normal to the plane

## Examples

``` LAMMPS
fix hold boundary planeforce 1.0 0.0 0.0
```

## Description

Adjust the forces on each atom in the group so that only the components
of force in the plane specified by the normal vector (x,y,z) remain.
This is done by subtracting out the component of force perpendicular to
the plane.

If the initial velocity of the atom is 0.0 (or in the plane), then it
should continue to move in the plane thereafter.

## Restart, fix_modify, output, run start/stop, minimize info

No information about this fix is written to [binary restart
files](restart). None of the [fix_modify](fix_modify) options are
relevant to this fix. No global or per-atom quantities are stored by
this fix for access by various [output commands](Howto_output). No
parameter of this fix can be used with the *start/stop* keywords of the
[run](run) command.

The forces due to this fix are imposed during an energy minimization,
invoked by the [minimize](minimize) command.

## Restrictions

> none

## Related commands

[fix lineforce](fix_lineforce)

## Default

none