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# compute plasticity/atom command

## Syntax

    compute ID group-ID plasticity/atom

- ID, group-ID are documented in compute command

- plasticity/atom = style name of this compute command

## Examples

    compute 1 all plasticity/atom

## Description

Define a computation that calculates the per-atom plasticity for each atom in a group. This is a quantity relevant for Peridynamics models. See this document for an overview of LAMMPS commands for Peridynamics modeling.

The plasticity for a Peridynamic particle is the so-called consistency parameter (\(\lambda\)). For elastic deformation, \(\lambda = 0\), otherwise \(\lambda > 0\) for plastic deformation. For details, see (Mitchell) and the PDF doc included in the LAMMPS distribution in doc/PDF/PDLammps_EPS.pdf.

This command can be invoked for one of the Peridynamic pair styles: peri/eps.

The plasticity value 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 page for an overview of LAMMPS output options.

The per-atom vector values are unitless numbers \(\lambda \ge 0.0\).

## Restrictions

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

## Related commands

compute damage/atom, compute dilatation/atom

## Default

none

(Mitchell) Mitchell, “A non-local, ordinary-state-based viscoelasticity model for peridynamics”, Sandia National Lab Report, 8064:1-28 (2011).