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# 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.

Note

Please note that the SPH PDF guide file has not been updated for many years and thus does not reflect the current syntax of the SPH package commands. For that please refer to the LAMMPS manual.

## 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 SPH package. It is only enabled if LAMMPS was built with that package. See the Build package page for more info.

## Related commands

fix sph/stationary

## Default

none