# fix particletemplate/superquadric command

## Syntax

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

- ID, group-ID are documented in fix command
- particletemplate/superquadric = 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 shape or blockiness

    atom_type value = atom type assigned to this particle template
    density values = constant param1
      param1 = constant density of particle material
    volume_limit value = lowest particle volume allowed in simulation
    shape values = constant a b c
      a, b, c = superquadric semi-axes
    blockiness values = constant n1 n2
      n1, n2 = superquadric blockiness parameters

## Examples

    fix pts1 all particletemplate/superquadric 123457 atom_type 1 density constant 2500 shape constant 0.0015 0.0025 0.0035 blockiness 4.0 4.0

## 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.

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.

This model is used in the framework of SUPERQUADRIC simulations. For more information see also the `SUPERQUADRIC guide`.

## 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

This fix requires atom_style superquadric. The blockiness values should be more or equal 2.

## Related commands

fix_particletemplate_sphere

## Default

a=1.0, b=1.0, c=1.0, n1=2.0, n2=2.0, atom_type = 1, volume_limit = 1e-12