# fix sph command

## Syntax

fix ID group-ID sph

• ID, group-ID are documented in fix command

• sph = style name of this fix command

## Examples

fix 1 all sph


## Description

Perform time integration to update position, velocity, internal energy and local density for atoms in the group each timestep. This fix is needed to time-integrate SPH systems where particles carry internal variables such as internal energy. SPH stands for Smoothed Particle Hydrodynamics.

See this PDF guide to using SPH in LAMMPS.

## 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. This fix is not invoked during energy minimization.

## Restrictions

This fix is part of the USER-SPH package. It is only enabled if LAMMPS was built with that package. See the Build package doc page for more info.

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