forked from lijiext/lammps
59 lines
1.6 KiB
HTML
59 lines
1.6 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 harmonic/shift 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 harmonic/shift
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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/shift
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bond_coeff 5 10.0 0.5 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>harmonic/shift</I> bond style is a shifted harmonic bond that uses
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the potential
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</P>
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<CENTER><IMG SRC = "Eqs/bond_harmonic_shift.jpg">
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</CENTER>
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<P>where r0 is the equilibrium bond distance, and rc the critical distance.
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The potential is -Umin at r0 and zero at rc. The spring constant is
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k = Umin / [ 2 (r0-rc)^2].
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</P>
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<P>The following coefficients must be defined for each bond type via the
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<A HREF = "bond_coeff.html">bond_coeff</A> command as in the example above, or in
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the data file or restart files read by the <A HREF = "read_data.html">read_data</A>
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or <A HREF = "read_restart.html">read_restart</A> commands:
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</P>
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<UL><LI>Umin (energy)
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</UL>
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<UL><LI>r0 (distance)
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</UL>
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<UL><LI>rc (distance)
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</UL>
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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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USER-MISC package. See the <A HREF = "Section_start.html#start_3">Making LAMMPS</A>
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section for more info on packages.
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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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<A HREF = "bond_harmonic.html">bond_harmonic</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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