fix particletemplate/multiplespheres command

Syntax

fix ID group-ID particletemplate/multiplespheres seed nspheres nspheresvalue keyword values ntry ntryvalue spheres (or spheres_different_types) values_spheres type mt opt_keyword opt_values
  • ID, group-ID are documented in fix command
  • particletemplate/multisphere = style name of this fix command
  • seed = random number generator seed (prime number greater 10000)
  • nspheres = obligatory keyword
  • nspheresvalue = number of spheres in the template (integer value)
  • zero or more keyword/value pairs can be appended
  • keyword, values are documented in fix particletemplate/sphere command
  • ntry = obligatory keyword
  • ntryvalue: number of tries for Monte Carlo approach
  • spheres or spheres_different_types = obligatory keyword
  • values_spheres = one out of the following options
option 1 (when keyword spheres is used) = file filename
option 2 (when keyword spheres is used) = file filename scale scalefactor
option 3 (when keyword spheres is used) = x1 y1 z1 r1 x2 y2 r2... where x/y/z are sphere positions and r are the radii
option 4 (when keyword spheres_different_types is used) = x1 y1 z1 t1 r1 x2 y2 r2 t2... where x/y/z are sphere positions, r are the radii and t the atom types
  • opt_keyword = bonded
bonded value = 'yes' or 'no'
    yes = bonds are created between adjacent spheres
    no = no bonds are created

Examples

fix pt1 all particletemplate/multiplespheres 123457 atom_type 2 density constant $*dens* nspheres 237 ntry 1000000 spheres file data/frag_hb2_v3.file scale 0.999999

Description

Define a particle template that is used as input for a fix_particledistribution_discrete command which contains not only one sphere, but multiple spheres. The particle parameters (positions, radii) are either defined manually as arguments to this command or via a text file, via the keyword file. The format of this text file is

x1 y1 z1 r1
x2 y2 z2 r2
...

and the number of lines in this file has to be equal to n_spheres as defined in this command. Comments can be made in this file via the ‘#’ character. Optionally, when a file is used for defining the multi-sphere template, keyword scale can be used to define a scalefactor to scale up or down the particle positions and radii.

In case keyword spheres_different_types is used, the textfile contains the type as last element in each line.

After the spheres are read, a Monte Carlo procedure is used to assess center of mass of the assembly.

Warning

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).

If the bonded keyword is set to ‘yes’ the spheres in one batch of n_spheres are bonded in case the cohesion model bond model is used and if the particeles satisfy the distance criterion of this model.

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

Default

radius = 1.0, density = 1.0