fix multisphere/break command — LIGGGHTS v3.X documentation

# fix multisphere/break command

## Syntax

    fix ID group-ID multisphere/break keyword value ...

- ID, group-ID are documented in fix command
- multisphere/break = style name of this fix command
- keywords = same as for fix multisphere, in addition: trigger_threshold and trigger_timeStep and trigger_fixName

    trigger_threshold value = x in units matching that of trigger_fixName
      this allows the user the specify a threshold value that will be compared with the per-atom value provided by trigger_fixName, e.g., the residence time in a region (e.g., computed via a fix property/atom/tracer/residencetime). if the threshold is exceeded, the multisphere particle will break.
    trigger_timeStep value = x in steps
      this allows the user to activate the fix after a predefined number of steps.
    trigger_fixName
      the user must specify the name of the fix that specified per-atom information that is used as the trigger value. The user can freely chose the fix, allowing a flexible use of this fix.

## Examples

fix integr grpMulti multisphere/break allow_group_and_set yes trigger_threshold 0.1 trigger_timeStep 0 trigger_fixName resTimeMill

## Description

The integration that is performed by this command is euqivalent to fix_multisphere. However, the user can trigger breakage events, which will destroy the “body” the atoms are in. The trigger is imiplemented such that in case the trigger value of one atom in a body exceeds the threshold value, the whole body will break. There are no fragments: all atoms that constitutea body will be released upon breakage.

WARNING: the atoms in a body MUST NOT overlap, since the atoms are simply released from the body without adjusting their size or their position.

## Restart, fix_modify, output, run start/stop, minimize info

Same as for fix_multisphere.

## Restrictions

Same as for fix_multisphere.

## Related commands

fix_multisphere

Default: none