forked from lijiext/lammps
78 lines
2.7 KiB
HTML
78 lines
2.7 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 hybrid 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 hybrid style1 style2 ...
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</PRE>
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<UL><LI>style1,style2 = list of one or more bond styles
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</UL>
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<P><B>Examples:</B>
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</P>
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<PRE>bond_style hybrid harmonic fene
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bond_coeff 1 harmonic 80.0 1.2
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bond_coeff 2* fene 30.0 1.5 1.0 1.0
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</PRE>
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<P><B>Description:</B>
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</P>
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<P>The <I>hybrid</I> style enables the use of multiple bond styles in one
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simulation. A bond style is assigned to each bond type. For example,
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bonds in a polymer flow (of bond type 1) could be computed with a
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<I>fene</I> potential and bonds in the wall boundary (of bond type 2) could
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be computed with a <I>harmonic</I> potential. The assignment of bond type
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to style is made via the <A HREF = "bond_coeff.html">bond_coeff</A> command or in
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the data file.
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</P>
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<P>In the bond_coeff commands, the name of a bond style must be added
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after the bond type, with the remaining coefficients being those
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appropriate to that style. In the example above, the 2 bond_coeff
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commands set bonds of bond type 1 to be computed with a <I>harmonic</I>
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potential with coefficients 80.0, 1.2 for K, r0. All other bond types
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(2-N) are computed with a <I>fene</I> potential with coefficients 30.0,
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1.5, 1.0, 1.0 for K, R0, epsilon, sigma.
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</P>
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<P>If bond coefficients are specified in the data file read via the
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<A HREF = "read_data.html">read_data</A> command, then the same rule applies.
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E.g. "harmonic" or "fene" must be added after the bond type, for each
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line in the "Bond Coeffs" section, e.g.
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</P>
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<PRE>Bond Coeffs
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</PRE>
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<PRE>1 harmonic 80.0 1.2
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2 fene 30.0 1.5 1.0 1.0
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...
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</PRE>
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<P>A bond style of <I>none</I> with no additional coefficients can be used in
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place of a bond style, either in a input script bond_coeff command or
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in the data file, if you desire to turn off interactions for specific
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bond types.
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</P>
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<P><B>Restrictions:</B>
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</P>
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<P>This bond style can only be used if LAMMPS was built with the
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MOLECULAR package (which it is by default). See the <A HREF = "Section_start.html#start_3">Making
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LAMMPS</A> section for more info on packages.
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</P>
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<P>Unlike other bond styles, the hybrid bond style does not store bond
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coefficient info for individual sub-styles in a <A HREF = "restart.html">binary restart
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files</A>. Thus when retarting a simulation from a restart
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file, you need to re-specify bond_coeff commands.
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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> none
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</P>
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</HTML>
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