forked from lijiext/lammps
60 lines
2.0 KiB
HTML
60 lines
2.0 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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</CENTER>
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<HR>
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<H3>fix spring/self command
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</H3>
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<P><B>Syntax:</B>
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</P>
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<PRE>fix ID group-ID spring/self K
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</PRE>
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<UL><LI>ID, group-ID are documented in <A HREF = "fix.html">fix</A> command
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<LI>spring/self = style name of this fix command
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<LI>K = spring constant (force/distance units)
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</UL>
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<P><B>Examples:</B>
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</P>
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<PRE>fix tether boundary-atoms spring/self 10.0
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</PRE>
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<P><B>Description:</B>
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</P>
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<P>Apply a spring force independently to each atom in the group to tether
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it to its initial position. The initial position for each atom is its
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location at the time the fix command was issued. At each timestep,
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the magnitude of the force on each atom is -Kr, where r is the
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displacement of the atom from its current position to its initial
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position.
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</P>
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<P><B>Restart, fix_modify, thermo output, run start/stop, minimize info:</B>
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</P>
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<P>This fix writes the original coordinates of tethered atoms to <A HREF = "restart.html">binary
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restart files</A>, so that the spring effect will be the
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same in a restarted simulation. See the
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<A HREF = "read_restart.html">read_restart</A> command for info on how to re-specify
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a fix in an input script that reads a restart file, so that the
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operation of the fix continues in an uninterrupted fashion.
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</P>
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<P>None of the <A HREF = "fix_modify.html">fix_modify</A> options are relevant to this
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fix. No quantities calculated by this fix can be output by the
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<A HREF = "thermo_style.html">thermo_style custom</A> command. No parameter of this
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fix can be used with the <I>start/stop</I> keywords of the <A HREF = "run.html">run</A>
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command. This fix is not invoked during <A HREF = "minimize.html">energy
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minimization</A>.
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</P>
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<P><B>Restrictions:</B> none
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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 = "fix_drag.html">fix drag</A>, <A HREF = "fix_spring.html">fix spring</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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