fix_modify AtC atom_weight command — LAMMPS documentation

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# fix_modify AtC atom_weight command

## Syntax

    fix_modify <AtC fixID> atom_weight <method> <args>

- AtC fixID = ID of fix atc instance

- atom_weight = name of the AtC sub-command

- method = constant or lattice or element or region or group or read_in

  - constant <group-ID> <value>: atoms in specified group are assigned the constant value given

  - lattice: volume per atom for specified lattice type (e.g. fcc) and parameter

  - element: element volume divided among atoms within element

  - region: volume per atom determined based on the atom count in the MD regions and their volumes. Note: meaningful only if atoms completely fill all the regions.

  - group: volume per atom determined based on the atom count in a group and its volume

  - node: (undocumented)

  - node_element: (undocumented)

  - read_in<filename>: list of values for atoms are read-in from specified file

## Examples

    fix_modify AtC atom_weight constant myatoms 11.8
    fix_modify AtC atom_weight lattice
    fix_modify AtC atom_weight read-in atm_wt_file.txt

## Description

Command for assigning the value of atomic weights used for atomic integration in atom-continuum coupled simulations.

## Restrictions

The use of the lattice option requires a lattice type and parameter is already specified.

## Related AtC commands

- fix_modify AtC command overview

## Default

lattice