# fix_modify AtC computes

## syntax

fix_modify AtC computes <add | delete> [per-atom compute id] <volume | number>

- add | delete (keyword) = add or delete the calculation of an equivalent continuum field for the specified per-atom compute as volume or number density quantity
- per-atom compute id = name/id for per-atom compute, fields can be calculated for all per-atom computes available from LAMMPS
- volume | number (keyword) = field created is a per-unit-volume quantity or a per-atom quantity as weighted by kernel functions

## examples

`compute virial all stress/atom`
`fix_modify AtC computes add virial volume`
`fix_modify AtC computes delete virial`
`compute centrosymmetry all centro/atom`
`fix_modify AtC computes add centrosymmetry number`

## description

Calculates continuum fields corresponding to specified per-atom computes created by LAMMPS

## restrictions

Must be used with the hardy/field type of AtC fix ( see fix atc command )
Per-atom compute must be specified before corresponding continuum field can be requested

## related

See manual page for compute

## default

No defaults exist for this command