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### 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 (integer value)
- 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' or 'uniform' or 'gaussian'
        param1 = density for 'constant', low value of density for 'uniform', expectancy value for 'gaussian'
          param2 = omitted for 'constant', high value of density for 'uniform', sigma value for 'gaussian'
      volume_limit value = lowest particle volume allowed in simulation
      radius values = random_style param1 (param2)
        random_style = 'constant' or 'uniform number' or 'uniform mass' or 'gaussian number'
        param1 = radius for 'constant', low value of radius for 'uniform', mu value for 'gaussian'
        param2 = omitted for 'constant', high value of radius for 'uniform', sigma value for 'gaussian'
      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 1 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, you can choose between 'constant', 'uniform' and 'gaussian' random styles. Note that for radius, you can additionally choose between a number-based and mass-based uniform distribution, where the latter is used more frequently typically. 'gaussian' for radius only supports a number-based distribution.

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!

It is thus possible to define a uniform or gaussian distribution on top of the discrete distribution defined by fix_particledistribution_discrete.

IMPORTANT NOTE: As opposed to the number-based distributions, this fix uses the more common distribution based on mass-% for the radius distribution (as does fix_particledistribution_discrete).

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