"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c

:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Section_commands.html#comm)

:line

fix efield command :h3

[Syntax:]

fix ID group-ID efield ex ey ez :pre

ID, group-ID are documented in "fix"_fix.html command
efield = style name of this fix command
ex,ey,ez = E-field component values (electric field units)
any of ex,ey,ez can be a variable (see below) :ul

[Examples:]

fix kick external-field efield 1.0 0.0 0.0
fix kick external-field efield 0.0 0.0 v_oscillate :pre

[Description:]

Add a force F = qE to each charged atom in the group due to an
external electric field being applied to the system.

Any of the 3 quantities defining the E-field components can be
specified as an equal-style or atom-style "variable"_variable.html,
namely {ex}, {ey}, {ez}.  If the value is a variable, it should be
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
determine the E-field component.

Equal-style variables can specify formulas with various mathematical
functions, and include "thermo_style"_thermo_style.html command
keywords for the simulation box parameters and timestep and elapsed
time.  Thus it is easy to specify a time-dependent E-field.

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.

[Restart, fix_modify, output, run start/stop, minimize info:]

No information about this fix is written to "binary restart
files"_restart.html.  None of the "fix_modify"_fix_modify.html options
are relevant to this fix.  No global or per-atom quantities are stored
by this fix for access by various "output
commands"_Section_howto.html#howto_15.  No parameter of this fix can
be used with the {start/stop} keywords of the "run"_run.html command.
This fix is not invoked during "energy minimization"_minimize.html.

[Restrictions:] none

[Related commands:]

"fix addforce"_fix_addforce.html

[Default:] none