# compute meso/rho/atom command

## Syntax

compute ID group-ID meso/rho/atom

• ID, group-ID are documented in compute command

• meso/rho/atom = style name of this compute command

## Examples

compute 1 all meso/rho/atom


## Description

Define a computation that calculates the per-atom mesoscopic density for each atom in a group.

The mesoscopic density is the mass density of a mesoscopic particle, calculated by kernel function interpolation using “pair style sph/rhosum”.

See this PDF guide to using SPH in LAMMPS.

The value of the mesoscopic 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 Howto output doc page for an overview of LAMMPS output options.

The per-atom vector values will be in mass/volume units.

## Restrictions

This compute 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.