forked from lijiext/lammps
86 lines
3.1 KiB
HTML
86 lines
3.1 KiB
HTML
<HTML>
|
|
<CENTER><A HREF = "http://lammps.sandia.gov">LAMMPS WWW Site</A> - <A HREF = "Manual.html">LAMMPS Documentation</A> - <A HREF = "Section_commands.html#comm">LAMMPS Commands</A>
|
|
</CENTER>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<HR>
|
|
|
|
<H3>create_atoms command
|
|
</H3>
|
|
<P><B>Syntax:</B>
|
|
</P>
|
|
<PRE>create_atoms type keyword values ...
|
|
</PRE>
|
|
<UL><LI>type = atom type (1-N) of atoms to create on a lattice
|
|
|
|
<LI>zero or more keyword/value pairs may be appended
|
|
|
|
<LI>keyword = <I>region</I> or <I>basis</I>
|
|
|
|
<PRE> <I>region</I> value = region-ID
|
|
region-ID = atoms will only be created if contained in the region
|
|
<I>basis</I> values = M itype
|
|
M = which basis atom
|
|
itype = atom type (1-N) to assign to the basis atom
|
|
</PRE>
|
|
|
|
</UL>
|
|
<P><B>Examples:</B>
|
|
</P>
|
|
<PRE>create_atoms 1
|
|
create_atoms 3 region regsphere
|
|
create_atoms 1 basis 2 5
|
|
</PRE>
|
|
<P><B>Description:</B>
|
|
</P>
|
|
<P>This command creates atoms on a lattice as an alternative to reading
|
|
in their coordinates via a <A HREF = "read_data.html">read_data</A> or
|
|
<A HREF = "read_restart.html">read_restart</A> command. A simulation box must
|
|
already exist, which is typically created via the
|
|
<A HREF = "create_box.html">create_box</A> command.
|
|
</P>
|
|
<P>Before using this command, a lattice must be defined using the
|
|
<A HREF = "lattice.html">lattice</A> 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 <A HREF = "region.html">region</A>
|
|
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.
|
|
</P>
|
|
<P>The <A HREF = "lattice.html">lattice</A> command specifies one or more basis atoms
|
|
in each unit cell. By default, when created, all basis atoms are
|
|
assigned the argument <I>type</I> as their atom type. The keyword <I>basis</I>
|
|
can be used to override the default for one or more basis atoms and
|
|
assign them a different atom type.
|
|
</P>
|
|
<P>By using the create_atoms command multiple times (interleaved with
|
|
<A HREF = "lattice.html">lattice</A> commands specifying different orientations),
|
|
grain boundaries can be created. Using the create_atoms command in
|
|
conjunction with the <A HREF = "delete_atoms.html">delete_atoms</A> 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.
|
|
</P>
|
|
<P>Created atoms are assigned a velocity of 0.0.
|
|
</P>
|
|
<P><B>Restrictions:</B>
|
|
</P>
|
|
<P>An <A HREF = "atom_style.html">atom_style</A> and <A HREF = "lattice.html">lattice</A> must be
|
|
previously defined to use this command.
|
|
</P>
|
|
<P><B>Related commands:</B>
|
|
</P>
|
|
<P><A HREF = "lattice.html">lattice</A>, <A HREF = "region.html">region</A>, <A HREF = "create_box.html">create_box</A>,
|
|
<A HREF = "read_data.html">read_data</A>, <A HREF = "read_restart.html">read_restart</A>
|
|
</P>
|
|
<P><B>Default:</B> none
|
|
</P>
|
|
</HTML>
|