2006-09-22 00:22:34 +08:00
|
|
|
<HTML>
|
|
|
|
|
<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>
|
|
|
|
|
</CENTER>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<HR>
|
|
|
|
|
|
|
|
|
|
<H3>fix efield command
|
|
|
|
|
</H3>
|
|
|
|
|
<P><B>Syntax:</B>
|
|
|
|
|
</P>
|
|
|
|
|
<PRE>fix ID group-ID efield ex ey ez
|
|
|
|
|
</PRE>
|
|
|
|
|
<UL><LI>ID, group-ID are documented in <A HREF = "fix.html">fix</A> command
|
|
|
|
|
<LI>efield = style name of this fix command
|
2010-04-22 06:47:54 +08:00
|
|
|
<LI>ex,ey,ez = E-field component values (electric field units)
|
|
|
|
|
<LI>any of ex,ey,ez can be a variable (see below)
|
2006-09-22 00:22:34 +08:00
|
|
|
</UL>
|
|
|
|
|
<P><B>Examples:</B>
|
|
|
|
|
</P>
|
2010-04-22 06:47:54 +08:00
|
|
|
<PRE>fix kick external-field efield 1.0 0.0 0.0
|
|
|
|
|
fix kick external-field efield 0.0 0.0 v_oscillate
|
2006-09-22 00:22:34 +08:00
|
|
|
</PRE>
|
|
|
|
|
<P><B>Description:</B>
|
|
|
|
|
</P>
|
|
|
|
|
<P>Add a force F = qE to each charged atom in the group due to an
|
|
|
|
|
external electric field being applied to the system.
|
|
|
|
|
</P>
|
2010-04-22 06:47:54 +08:00
|
|
|
<P>Any of the 3 quantities defining the E-field components can be
|
2010-04-27 22:33:02 +08:00
|
|
|
specified as an equal-style or atom-style <A HREF = "variable.html">variable</A>,
|
|
|
|
|
namely <I>ex</I>, <I>ey</I>, <I>ez</I>. If the value is a variable, it should be
|
2010-08-13 07:10:38 +08:00
|
|
|
specified as v_name, where name is the variable name. In this case,
|
|
|
|
|
the variable will be evaluated each timestep, and its value used to
|
2010-04-27 22:33:02 +08:00
|
|
|
determine the E-field component.
|
2010-04-22 06:47:54 +08:00
|
|
|
</P>
|
|
|
|
|
<P>Equal-style variables can specify formulas with various mathematical
|
|
|
|
|
functions, and include <A HREF = "thermo_style.html">thermo_style</A> command
|
|
|
|
|
keywords for the simulation box parameters and timestep and elapsed
|
|
|
|
|
time. Thus it is easy to specify a time-dependent E-field.
|
|
|
|
|
</P>
|
|
|
|
|
<P>Atom-style variables can specify the same formulas as equal-style
|
|
|
|
|
variables but can also include per-atom values, such as atom
|
|
|
|
|
coordinates. Thus it is easy to specify a spatially-dependent E-field
|
|
|
|
|
with optional time-dependence as well.
|
|
|
|
|
</P>
|
2007-10-11 06:28:11 +08:00
|
|
|
<P><B>Restart, fix_modify, output, run start/stop, minimize info:</B>
|
2007-06-26 08:03:39 +08:00
|
|
|
</P>
|
|
|
|
|
<P>No information about this fix is written to <A HREF = "restart.html">binary restart
|
|
|
|
|
files</A>. None of the <A HREF = "fix_modify.html">fix_modify</A> options
|
2010-04-03 00:51:06 +08:00
|
|
|
are relevant to this fix. No global or per-atom quantities are stored
|
2011-08-26 01:01:01 +08:00
|
|
|
by this fix for access by various <A HREF = "Section_howto.html#howto_15">output
|
|
|
|
|
commands</A>. No parameter of this fix can
|
|
|
|
|
be used with the <I>start/stop</I> keywords of the <A HREF = "run.html">run</A> command.
|
2007-10-11 06:28:11 +08:00
|
|
|
This fix is not invoked during <A HREF = "minimize.html">energy minimization</A>.
|
2007-06-26 08:03:39 +08:00
|
|
|
</P>
|
2006-09-22 00:22:34 +08:00
|
|
|
<P><B>Restrictions:</B> none
|
|
|
|
|
</P>
|
|
|
|
|
<P><B>Related commands:</B>
|
|
|
|
|
</P>
|
|
|
|
|
<P><A HREF = "fix_addforce.html">fix addforce</A>
|
|
|
|
|
</P>
|
|
|
|
|
<P><B>Default:</B> none
|
|
|
|
|
</P>
|
|
|
|
|
</HTML>
|
