forked from lijiext/lammps
94 lines
3.6 KiB
HTML
94 lines
3.6 KiB
HTML
<HTML>
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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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<HR>
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<H3>bond_style command
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</H3>
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<P><B>Syntax:</B>
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</P>
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<PRE>bond_style style args
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</PRE>
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<UL><LI>style = <I>none</I> or <I>hybrid</I> or <I>class2</I> or <I>fene</I> or <I>fene/expand</I> or <I>harmonic</I> or <I>morse</I> or <I>nonlinear</I> or <I>quartic</I>
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</UL>
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<PRE> args = none for any style except <I>hybrid</I>
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<I>hybrid</I> args = list of one or more styles
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</PRE>
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<P><B>Examples:</B>
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</P>
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<PRE>bond_style harmonic
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bond_style fene
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bond_style hybrid harmonic fene
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</PRE>
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<P><B>Description:</B>
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</P>
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<P>Set the formula(s) LAMMPS uses to compute bond interactions between
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pairs of atoms. In LAMMPS, a bond differs from a pairwise
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interaction, which are set via the <A HREF = "pair_style.html">pair_style</A>
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command. Bonds are defined between specified pairs of atoms and
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remain in force for the duration of the simulation (unless the bond
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breaks which is possible in some bond potentials). The list of bonded
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atoms is read in by a <A HREF = "read_data.html">read_data</A> or
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<A HREF = "read_restart.html">read_restart</A> command from a data or restart file.
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By contrast, pair potentials are defined between pairs of atoms that
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are within a cutoff distance and the set of active interactions
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typically changes over time.
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</P>
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<P>Hybrid models where bonds are computed using different bond potentials
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can be setup using the <I>hybrid</I> bond style.
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</P>
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<P>The coefficients associated with a bond style can be specified in a
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data or restart file or via the <A HREF = "bond_coeff.html">bond_coeff</A> command.
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</P>
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<P>In the formulas listed for each bond style, <I>r</I> is the distance
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between the 2 atoms in the bond.
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</P>
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<P>Note that when both a bond and pair style is defined, the
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<A HREF = "special_bond.html">special_bond</A> command often needs to be used to
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turn off (or weight) the pairwise interaction that would otherwise
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exist between 2 bonded atoms.
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</P>
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<HR>
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<P>Here is an alphabetic list of bond styles defined in LAMMPS. Click on
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the style to display the formula it computes and coefficients
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specified by the associated <A HREF = "bond_coeff.html">bond_coeff</A> command:
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</P>
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<UL><LI><A HREF = "bond_style_none.html">bond_style none</A> - turn off bonded interactions
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<LI><A HREF = "bond_style_hybrid.html">bond_style hybrid</A> - define multiple styles of bond interactions
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</UL>
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<UL><LI><A HREF = "bond_style_class2.html">bond_style class2</A> - COMPASS (class 2) bond
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<LI><A HREF = "bond_style_fene.html">bond_style fene</A> - FENE (finite-extensible non-linear elastic) bond
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<LI><A HREF = "bond_style_fene_expand.html">bond_style fene/expand</A> - FENE bonds with variable size particles
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<LI><A HREF = "bond_style_harmonic.html">bond_style harmonic</A> - harmonic bond
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<LI><A HREF = "bond_style_morse.html">bond_style morse</A> - Morse bond
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<LI><A HREF = "bond_style_nonlinear.html">bond_style nonlinear</A> - nonlinear bond
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<LI><A HREF = "bond_style_quartic.html">bond_style quartic</A> - breakable quartic bond
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</UL>
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<HR>
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<P><B>Restrictions:</B>
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</P>
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<P>Bond styles can only be set for atom styles that allow bonds to be
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defined.
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</P>
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<P>Bond styles are part of the "molecular" package. They are only
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enabled if LAMMPS was built with that package. See the <A HREF = "Section_start.html#2_2">Making
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LAMMPS</A> section for more info.
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</P>
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<P><B>Related commands:</B>
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</P>
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<P><A HREF = "bond_coeff.html">bond_coeff</A>, <A HREF = "delete_bonds.html">delete_bonds</A>
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</P>
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<P><B>Default:</B>
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</P>
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<P>bond_style none
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</P>
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</HTML>
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