lammps/doc/create_atoms.txt

"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c

:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Section_commands.html#comm)

:line

create_atoms command :h3

[Syntax:]

create_atoms type keyword values ... :pre

type = atom type (1-N) of atoms to create on a lattice :ulb,l
zero or more keyword/value pairs may be appended :l
keyword = {region} or {basis} :l
  {region} value = region-ID
    region-ID = atoms will only be created if contained in the region
  {basis} values = M itype
    M = which basis atom
    itype = atom type (1-N) to assign to the basis atom :pre
:ule

[Examples:]

create_atoms 1
create_atoms 3 region regsphere
create_atoms 1 basis 2 5 :pre

[Description:]

This command creates atoms on a lattice as an alternative to reading
in their coordinates via a "read_data"_read_data.html or
"read_restart"_read_restart.html command.  A simulation box must
already exist, which is typically created via the
"create_box"_create_box.html command.

Before using this command, a lattice must be defined using the
"lattice"_lattice.html command.  If a region is not specified, the
create_atoms command fills the entire simulation box with atoms on the
lattice.  If a region is specified (see the "region"_region.html
command), then the geometric volume is filled that is inside the
simulation box and is also consistent with the region volume.  Note
that a region can be specified so that its "volume" is either inside
or outside a geometric boundary.

The "lattice"_lattice.html command specifies one or more basis atoms
in each unit cell.  By default, when created, all basis atoms are
assigned the argument {type} as their atom type.  The keyword {basis}
can be used to override the default for one or more basis atoms and
assign them a different atom type.

By using the create_atoms command multiple times (interleaved with
"lattice"_lattice.html commands specifying different orientations),
grain boundaries can be created.  Using the create_atoms command in
conjunction with the "delete_atoms"_delete_atoms.html command,
reasonably complex geometries can be created.  The create_atoms
command can also be used to add atoms to a system previously read in
from a data or restart file.  In all these cases, care should be taken
to insure that new atoms do not overlap existing atoms
inappropriately.

Created atoms are assigned a velocity of 0.0.

[Restrictions:]

An "atom_style"_atom_style.html and "lattice"_lattice.html must be
previously defined to use this command.

[Related commands:]

"lattice"_lattice.html, "region"_region.html, "create_box"_create_box.html,
"read_data"_read_data.html, "read_restart"_read_restart.html

[Default:] none