\(\renewcommand{\AA}{\text{Å}}\)

# fix enforce2d command

Accelerator Variants: enforce2d/kk

## Syntax

    fix ID group-ID enforce2d

- ID, group-ID are documented in fix command

- enforce2d = style name of this fix command

## Examples

    fix 5 all enforce2d

## Description

Zero out the z-dimension velocity and force on each atom in the group. This is useful when running a 2d simulation to ensure that atoms do not move from their initial z coordinate.

Styles with a gpu, intel, kk, omp, or opt suffix are functionally the same as the corresponding style without the suffix. They have been optimized to run faster, depending on your available hardware, as discussed on the Accelerator packages page. The accelerated styles take the same arguments and should produce the same results, except for round-off and precision issues.

These accelerated styles are part of the GPU, INTEL, KOKKOS, OPENMP, and OPT packages, respectively. They are only enabled if LAMMPS was built with those packages. See the Build package page for more info.

You can specify the accelerated styles explicitly in your input script by including their suffix, or you can use the -suffix command-line switch when you invoke LAMMPS, or you can use the suffix command in your input script.

See the Accelerator packages page for more instructions on how to use the accelerated styles effectively.

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

No information about this fix is written to binary restart files. None of the 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. No parameter of this fix can be used with the start/stop keywords of the run command.

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

## Restrictions

none

## Related commands

none

## Default

none