2006-09-22 00:22:34 +08:00
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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>fix efield 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 efield ex ey ez
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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>efield = style name of this fix command
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2010-04-22 06:47:54 +08:00
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<LI>ex,ey,ez = E-field component values (electric field units)
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<LI>any of ex,ey,ez can be a variable (see below)
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2006-09-22 00:22:34 +08:00
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</UL>
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<P><B>Examples:</B>
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</P>
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2010-04-22 06:47:54 +08:00
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<PRE>fix kick external-field efield 1.0 0.0 0.0
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fix kick external-field efield 0.0 0.0 v_oscillate
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2006-09-22 00:22:34 +08:00
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</PRE>
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<P><B>Description:</B>
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</P>
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<P>Add a force F = qE to each charged atom in the group due to an
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external electric field being applied to the system.
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</P>
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2010-04-22 06:47:54 +08:00
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<P>Any of the 3 quantities defining the E-field components can be
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2010-04-27 22:33:02 +08:00
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specified as an equal-style or atom-style <A HREF = "variable.html">variable</A>,
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namely <I>ex</I>, <I>ey</I>, <I>ez</I>. If the value is a variable, it should be
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specified as v_ID, where ID is the variable ID. In this case, the
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variable will be evaluated each timestep, and its value used to
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determine the E-field component.
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2010-04-22 06:47:54 +08:00
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</P>
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<P>Equal-style variables can specify formulas with various mathematical
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functions, and include <A HREF = "thermo_style.html">thermo_style</A> command
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keywords for the simulation box parameters and timestep and elapsed
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time. Thus it is easy to specify a time-dependent E-field.
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</P>
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<P>Atom-style variables can specify the same formulas as equal-style
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variables but can also include per-atom values, such as atom
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coordinates. Thus it is easy to specify a spatially-dependent E-field
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with optional time-dependence as well.
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</P>
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2007-10-11 06:28:11 +08:00
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<P><B>Restart, fix_modify, output, run start/stop, minimize info:</B>
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2007-06-26 08:03:39 +08:00
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</P>
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<P>No information about this fix is written to <A HREF = "restart.html">binary restart
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files</A>. None of the <A HREF = "fix_modify.html">fix_modify</A> options
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2010-04-03 00:51:06 +08:00
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are relevant to this fix. No global or per-atom quantities are stored
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by this fix for access by various <A HREF = "Section_howto.html#4_15">output
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2007-10-11 06:28:11 +08:00
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commands</A>. No parameter of this fix can be
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used with the <I>start/stop</I> keywords of the <A HREF = "run.html">run</A> command.
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This fix is not invoked during <A HREF = "minimize.html">energy minimization</A>.
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2007-06-26 08:03:39 +08:00
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</P>
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2006-09-22 00:22:34 +08:00
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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_addforce.html">fix addforce</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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