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<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>
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<H3>pair_style hybrid command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>pair_style hybrid style1 style2 ...
</PRE>
<UL><LI>style1,style2 = list of one or more pair styles
</UL>
<P><B>Examples:</B>
</P>
<PRE>pair_style hybrid lj/charmm/coul/long 10.0 eam
pair_coeff 1*2 1*2 eam niu3
pair_coeff 3 3 lj/cut/coul/cut 1.0 1.0
pair_coeff 1*2 3 lj/cut 0.5 1.2
</PRE>
<P><B>Description:</B>
</P>
<P>The <I>hybrid</I> style enables the use of multiple pair styles in one
simulation. A pair style can be assigned to each pair of atom types
via the <A HREF = "pair_coeff.html">pair_coeff</A> command.
</P>
<P>For example, a metal on a LJ surface could be computed where the metal
atoms interact with each other via a <I>eam</I> potential, the surface
atoms interact with each other via a <I>lj/cut</I> potential, and the
metal/surface interaction is also via a <I>lj/cut</I> potential.
</P>
<P>All pair styles that will be used must be listed in the pair_style
hybrid command (in any order). The name of each sub-style is followed
by its arguments, as illustrated in the example above.
</P>
<P>In the pair_coeff command, the first coefficient sets the pair style
and the remaining coefficients are those appropriate to that style.
For example, consider a simulation with 3 atom types: types 1 and 2
are Ni atoms, type 3 are LJ atoms with charges. The following
commands would set up a hybrid simulation:
</P>
<PRE>pair_style hybrid eam/alloy lj/cut/coul/cut 10.0 lj/cut 8.0
pair_coeff * * eam/alloy nialhjea 1 1 0
pair_coeff 3 3 lj/cut/coul/cut 1.0 1.0
pair_coeff 1*2 3 lj/cut 0.8 1.1
</PRE>
<P>Note that as with any pair_style, coeffs must be defined for all I,J
interactions. If the sub-style allows for mixing (see the
<A HREF = "pair_modify.html">pair_modify</A> command), then I,J interactions between
atom types which both are assigned to that sub-style do not need to be
specified. I.e. if atom types 1 and 2 are both computed with <I>lj/cut</I>
and coeffs for 1,1 and 2,2 interactions are specified, then coeffs for
1,2 interactions will be generated automatically via mixing.
</P>
<P>If the pair_coeff command for a sub-style requires the use of * * as
atom type arguments (e.g. the <I>eam/alloy</I> example above), then it will
also include trailing arguments which map atom types to elements in
the potential. These mapping arguments should be specified as 0 if
the sub-style is not being applied to certain atom types.
</P>
<P>Note that you may also need to use an <A HREF = "atom_style.html">atom_style</A>
hybrid command in your input script, if atoms in the simulation will
have attributes from several atom styles, due to using multiple pair
potentials.
</P>
<P><B>Restrictions:</B>
</P>
<P>When using a long-range Coulomic solver (via the
<A HREF = "kspace_style">kspace_style</A> command) with pair_style hybrid, one or
more sub-styles will be of the "long" variety.
E.g. <I>lj/cut/coul/long</I> or <I>buck/coul/long</I>. It is OK to have more
than one sub-style with a "long" component, but you must insure that
the short-range Coulombic cutoff used by each of these pair styles is
consistent. Else the long-range Coulombic solve will be inconsistent.
</P>
<P>A pair style of <I>none</I> can be specified as an argument to pair_style
hybrid and the corresponding pair_coeff commands, if you desire to
turn off pairwise interactions between certain pairs of atom types.
</P>
<P>The hybrid style cannot include any of the <I>granular</I> styles in its
list of styles to use.
</P>
<P>If you use multiple <I>coul/long</I> pair styles along with a <A HREF = "kspace_style.html">kspace
style</A>, then you should make sure the pairwise
Coulombic cutoff is the same for all the pair styles.
</P>
<P><B>Related commands:</B>
</P>
<P><A HREF = "pair_coeff.html">pair_coeff</A>
</P>
<P><B>Default:</B> none
</P>
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