.. index:: compute sph/rho/atom

compute sph/rho/atom command
============================

Syntax
""""""

.. code-block:: LAMMPS

   compute ID group-ID sph/rho/atom

* ID, group-ID are documented in :doc:`compute <compute>` command
* sph/rho/atom = style name of this compute command

Examples
""""""""

.. code-block:: LAMMPS

   compute 1 all sph/rho/atom

Description
"""""""""""

Define a computation that calculates the per-atom SPH density for each
atom in a group, i.e. a Smooth-Particle Hydrodynamics density.

The SPH density is the mass density of an SPH particle, calculated by
kernel function interpolation using "pair style sph/rhosum".

See `this PDF guide <PDF/SPH_LAMMPS_userguide.pdf>`_ 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.

The value of the SPH density will be 0.0 for atoms not in the
specified compute group.

Output info
"""""""""""

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

The per-atom vector values will be in mass/volume :doc:`units <units>`.

Restrictions
""""""""""""

This compute is part of the SPH package.  It is only enabled if
LAMMPS was built with that package.  See the :doc:`Build package <Build_package>` page for more info.

Related commands
""""""""""""""""

:doc:`dump custom <dump>`

Default
"""""""

none
