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# compute smd/ulsph/strain/rate command¶

## Syntax¶

compute ID group-ID smd/ulsph/strain/rate

• ID, group-ID are documented in compute command

• smd/ulsph/strain/rate = style name of this compute command

## Examples¶

compute 1 all smd/ulsph/strain/rate


## Description¶

Define a computation that outputs the rate of the logarithmic strain tensor for particles interacting via the updated Lagrangian SPH pair style.

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

The values will be given in units of one over time.

The per-particle vector has 6 entries, corresponding to the xx, yy, zz, xy, xz, yz components of the symmetric strain rate tensor.

## Restrictions¶

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

This compute can only be used for particles which interact with the updated Lagrangian SPH pair style.

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