fix particletemplate/sphere command — LIGGGHTS v3.X documentation

# fix particletemplate/sphere command

## Syntax

    fix ID group-ID particletemplate/sphere seed keyword values ...

- ID, group-ID are documented in fix command
- particletemplate/sphere = style name of this fix command
- seed = random number generator seed (prime number greater 10000)
- zero or more keyword/value pairs can be appended
- keyword = atom_type or density or volume_limit or radius or relative

    atom_type value = atom type assigned to this particle template
    density values = random_style param1 (param2)
      random_style = 'constant'
      param1 = density for 'constant',
        param2 = omitted for 'constant'
    volume_limit value = lowest particle volume allowed in simulation
    radius values = random_style param1 (param2)
      random_style = 'constant'
      param1 = radius for 'constant'
      param2 = omitted for 'constant'
    relative value = yes or no
      no = set a flag for other commands that radius given here is abosulute (in length units)
      yes = set a flag for other commands that radius given here is relative (in % of a reference radius)

## Examples

    fix pts1 all particletemplate/sphere 123457 atom_type 1 density constant 2500 radius constant 0.0015

## Description

Define a particle that is used as input for a fix_particledistribution_discrete command. You can choose the atom type, density and radius of the particles. For density and radius, there is currently only a ‘constant’ style. Note that this is not a restriction since multiple commands of style particletemplate/sphere can be used in a fix_particledistribution_discrete command so any kind of distribution can be approximated to any arbitrary precision.

Keyword relative lets the user set a flag to let other commands know if the radii specified by this command are absolute (length units) or relative (in % of a reference radius). IMPORTANT NOTE: This setting should not be changed away from the default value (no) unless explicity required by another command!

LIGGGHTS(R)-PUBLIC will throw an error if the particle volume is too small compared to machine precision. If you are sure you know what you are doing you can override the default limit of 1e-12.

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

Information about the random state in this fix is written to binary restart files so you can restart a simulation with the same particles being chosen for insertion. None of the fix_modify options are relevant to this fix. No global scalar or vector or per-atom quantities are stored by this fix for access by various output commands. No parameter of this fix can be used with the start/stop keywords of the run command. This fix is not invoked during `energy minimization`.

## Restrictions

> none

## Related commands

fix_particletemplate_sphere

## Default

radius = 1.0, density = 1.0, atom_type = 1, volume_limit = 1e-12, relative = no