forked from lijiext/lammps
102 lines
4.2 KiB
HTML
102 lines
4.2 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>atom_style command
|
|
</H3>
|
|
<P><B>Syntax:</B>
|
|
</P>
|
|
<PRE>atom_style style args
|
|
</PRE>
|
|
<UL><LI>style = <I>angle</I> or <I>atomic</I> or <I>bond</I> or <I>charge</I> or <I>dipole</I> or <I>dpd</I> or <I>ellipsoid</I> or <I>full</I> or <I>granular</I> or <I>molecular</I> or <I>peri</I> or <I>hybrid</I>
|
|
</UL>
|
|
<PRE> args = none for any style except <I>hybrid</I>
|
|
<I>hybrid</I> args = list of one or more sub-styles
|
|
</PRE>
|
|
<P><B>Examples:</B>
|
|
</P>
|
|
<PRE>atom_style atomic
|
|
atom_style bond
|
|
atom_style full
|
|
atom_style hybrid charge bond
|
|
</PRE>
|
|
<P><B>Description:</B>
|
|
</P>
|
|
<P>Define what style of atoms to use in a simulation. This determines
|
|
what attributes are associated with the atoms. This command must be
|
|
used before a simulation is setup via a <A HREF = "read_data.html">read_data</A>,
|
|
<A HREF = "read_restart.html">read_restart</A>, or <A HREF = "create_box.html">create_box</A>
|
|
command.
|
|
</P>
|
|
<P>Once a style is assigned, it cannot be changed, so use a style general
|
|
enough to encompass all attributes. E.g. with style <I>bond</I>, angular
|
|
terms cannot be used or added later to the model. It is OK to use a
|
|
style more general than needed, though it may be slightly inefficient.
|
|
</P>
|
|
<P>The choice of style affects what quantities are stored by each atom,
|
|
what quantities are communicated between processors to enable forces
|
|
to be computed, and what quantities are listed in the data file read
|
|
by the <A HREF = "read_data.html">read_data</A> command.
|
|
</P>
|
|
<P>These are the attributes of each style. All styles store coordinates,
|
|
velocities, atom IDs and types.
|
|
</P>
|
|
<UL><LI><I>angle</I> = bonds and angles - e.g. bead-spring polymers with stiffness
|
|
<LI><I>atomic</I> = only the default values
|
|
<LI><I>bond</I> = bonds - e.g. bead-spring polymers
|
|
<LI><I>charge</I> = charge
|
|
<LI><I>dipole</I> = charge and dipole moment
|
|
<LI><I>dpd</I> = default values, also communicates velocities
|
|
<LI><I>ellipsoid</I> = quaternion for particle orientation, angular velocity/momentum
|
|
<LI><I>full</I> = molecular + charge - e.g. biomolecules, charged polymers
|
|
<LI><I>granular</I> = granular atoms with rotational properties
|
|
<LI><I>molecular</I> = bonds, angles, dihedrals, impropers - e.g. all-atom polymers
|
|
<LI><I>peri</I> = mass, volume - e.g. mesocopic Peridynamics
|
|
</UL>
|
|
<P>Typically, simulations require only a single (non-hybrid) atom style.
|
|
If some atoms in the simulation do not have all the properties defined
|
|
by a particular style, use the simplest style that defines all the
|
|
needed properties by any atom. For example, if some atoms in a
|
|
simulation are charged, but others are not, use the <I>charge</I> style.
|
|
If some atoms have bonds, but others do not, use the <I>bond</I> style.
|
|
The only scenario where the <I>hybrid</I> style is needed is if there is no
|
|
single style which defines all needed properties of all atoms.
|
|
E.g. if you want charged DPD particles, you would need to use
|
|
"atom_style hybrid dpd charge". When a hybrid style is used, atoms
|
|
store and communicate the union of all quantities implied by the
|
|
individual styles.
|
|
</P>
|
|
<P>LAMMPS can be extended with new atom styles; see <A HREF = "Section_modify.html">this
|
|
section</A>.
|
|
</P>
|
|
<P><B>Restrictions:</B>
|
|
</P>
|
|
<P>This command cannot be used after the simulation box is defined by a
|
|
<A HREF = "read_data.html">read_data</A> or <A HREF = "create_box.html">create_box</A> command.
|
|
</P>
|
|
<P>The <I>angle</I>, <I>bond</I>, <I>full</I>, and <I>molecular</I> styles are part of the
|
|
"molecular" package. The <I>granular</I> style is part of the "granular"
|
|
package. The <I>dpd</I> style is part of the "dpd" package. The <I>dipole</I>
|
|
style is part of the "dipole" package. The <I>ellipsoid</I> style is part
|
|
of the "ellipsoid" package. The <I>peri</I> style is part of the "peri"
|
|
package for Peridynamics. They are only enabled if LAMMPS was built
|
|
with that package. See the <A HREF = "Section_start.html#2_3">Making LAMMPS</A>
|
|
section for more info.
|
|
</P>
|
|
<P><B>Related commands:</B>
|
|
</P>
|
|
<P><A HREF = "read_data.html">read_data</A>, <A HREF = "pair_style.html">pair_style</A>
|
|
</P>
|
|
<P><B>Default:</B>
|
|
</P>
|
|
<P>atom_style atomic
|
|
</P>
|
|
</HTML>
|