fix_modify AtC rates command — LAMMPS documentation

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# fix_modify AtC rates command

## Syntax

    fix_modify <AtC fixID> rates <add|delete> <list_of_fields>

- AtC fixID = ID of fix atc instance

- rates = name of the AtC sub-command

- add or delete = select whether to add or delete calculation of rates for the listed output fields

- list_of_fields = one or more of the fields listed below:

  - density : mass per unit volume

  - displacement : displacement vector

  - momentum : momentum per unit volume

  - velocity : defined by momentum divided by density

  - projected_velocity : simple kernel estimation of atomic velocities

  - temperature : temperature derived from the relative atomic kinetic energy

  - kinetic_temperature : temperature derived from the full kinetic energy

  - number_density : simple kernel estimation of number of atoms per unit volume

  - stress : Cauchy stress tensor for eulerian analysis (atom_element_map), or first Piola-Kirchhoff stress tensor for lagrangian analysis

  - transformed_stress : first Piola-Kirchhoff stress tensor for eulerian analysis (atom_element_map), or Cauchy stress tensor for lagrangian analysis

  - heat_flux : spatial heat flux vector for eulerian, or referential heat flux vector for lagrangian

  - potential_energy : potential energy per unit volume

  - kinetic_energy : kinetic energy per unit volume

  - thermal_energy : thermal energy (kinetic energy - continuum kinetic energy) per unit volume

  - internal_energy : total internal energy (potential + thermal) per unit volume

  - energy : total energy (potential + kinetic) per unit volume

  - number_density : number of atoms per unit volume

  - eshelby_stress : configurational stress (energy-momentum) tensor defined by [Eshelby]

  - vacancy_concentration : volume fraction of vacancy content

  - type_concentration : volume fraction of a specific atom type

## Examples

    fix_modify AtC rates add temperature velocity stress
    fix_modify AtC rates delete stress

## Description

Requests calculation and output of rates (time derivatives) of the fields from the AtC transfer class. For Eulerian analysis (see fix_modify AtC atom_element_map) these rates are the partial time derivatives of the nodal fields, not the full (material) time derivatives.

## Restrictions

Must be used with fix atc hardy.

## Related AtC commands

- fix_modify AtC command overview

- fix_modify AtC atom_element_map

- fix_modify AtC fields

- fix_modify AtC fields

## Default

None.