\(\renewcommand{\AA}{\text{Å}}\)

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.

Default

None.

References

(Eshelby) J.D. Eshelby, Philos. Trans. Royal Soc. London A, Math. Phys. Sci., Vol. 244, No. 877 (1951) pp. 87-112; J. Elasticity, Vol. 5, Nos. 3-4 (1975) pp. 321-335]