# compute smd/ulsph/stress command

## Syntax

compute ID group-ID smd/ulsph/stress

• ID, group-ID are documented in compute command
• smd/ulsph/stress = style name of this compute command

## Examples

compute 1 all smd/ulsph/stress


## Description

Define a computation that outputs the Cauchy stress tensor.

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

Output info:

This compute calculates a per-particle vector of vectors (tensors), which can be accessed by any command that uses per-particle values from a compute as input. See Section 6.15 for an overview of LAMMPS output options.

The values will be given in units of pressure.

The per-particle vector has 7 entries. The first six entries correspond to the xx, yy, zz, xy, xz, yz components of the symmetric Cauchy stress tensor. The seventh entry is the second invariant of the stress tensor, i.e., the von Mises equivalent stress.

## Restrictions

This compute is part of the USER-SMD package. It is only enabled if LAMMPS was built with that package. See the Making LAMMPS section for more info. This compute can only be used for particles which interact with the updated Lagrangian SPH pair style.