# compute smd/rho command

## Syntax

compute ID group-ID smd/rho

• ID, group-ID are documented in compute command

• smd/rho = style name of this compute command

## Examples

compute 1 all smd/rho


## Description

Define a computation that calculates the per-particle mass density. The mass density is the mass of a particle which is constant during the course of a simulation, divided by its volume, which can change due to mechanical deformation.

See this PDF guide to use Smooth Mach Dynamics in LAMMPS.

Output info:

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

The per-particle values will be in units of mass over volume.

## Restrictions

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