Page Menu
Home
c4science
Search
Configure Global Search
Log In
Files
F96341677
fix_wall_lj93.html
No One
Temporary
Actions
Download File
Edit File
Delete File
View Transforms
Subscribe
Mute Notifications
Award Token
Subscribers
None
File Metadata
Details
File Info
Storage
Attached
Created
Wed, Dec 25, 14:59
Size
3 KB
Mime Type
text/html
Expires
Fri, Dec 27, 14:59 (1 d, 12 h)
Engine
blob
Format
Raw Data
Handle
23150838
Attached To
rLAMMPS lammps
fix_wall_lj93.html
View Options
<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 wall/lj93 command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>fix ID group-ID wall/lj93 style coord epsilon sigma cutoff
</PRE>
<UL><LI>ID, group-ID are documented in <A HREF = "fix.html">fix</A> command
<LI>wall/lj93 = style name of this fix command
<LI>style = <I>xlo</I> or <I>xhi</I> or <I>ylo</I> or <I>yhi</I> or <I>zlo</I> or <I>zhi</I>
<LI>coord = position of wall
<LI>epsilon = Lennard-Jones epsilon for wall-particle interaction
<LI>sigma = Lennard-Jones sigma for wall-particle interaction
<LI>cutoff = distance from wall at which wall-particle interaction is cut off
</UL>
<P><B>Examples:</B>
</P>
<PRE>fix wallhi all wall/lj93 xhi 10.0 1.0 1.0 2.5
</PRE>
<P><B>Description:</B>
</P>
<P>Bound the simulation domain with a Lennard-Jones wall that encloses
the atoms. The energy E of a wall-particle interactions is given by
the 9-3 potential
</P>
<CENTER><IMG SRC = "Eqs/fix_wall_lj93.jpg">
</CENTER>
<P>where <I>r</I> is the distance from the particle to the wall <I>coord</I>, and
epsilon and sigma are the usual LJ parameters. Rc is the cutoff value
specified in the command. This interaction is derived by integrating
over a 3d half-lattice of Lennard-Jones 12-6 particles. A harder,
more repulsive wall interaction can be computed by using the <A HREF = "fix_wall_lj126.html">fix
wall/lj126</A> command.
</P>
<P>The wall potential is shifted so that the energy of a wall-particle
interaction is 0.0 at the cutoff distance.
</P>
<P><B>Restart, fix_modify, output, run start/stop, minimize info:</B>
</P>
<P>No information about this fix is written to <A HREF = "restart.html">binary restart
files</A>.
</P>
<P>The <A HREF = "fix_modify.html">fix_modify</A> <I>energy</I> option is supported by this
fix to add the energy of interaction between atoms and the wall to the
system's potential energy as part of <A HREF = "thermo_style.html">thermodynamic
output</A>.
</P>
<P>This fix computes a scalar energy and a 3-vector of forces (on the
wall), which can be accessed by various <A HREF = "Section_howto.html#4_15">output
commands</A>. The scalar and vector values
calculated by this fix are "extensive", meaning they scale with the
number of atoms in the simulation.
</P>
<P>No parameter of this fix can be used with the <I>start/stop</I> keywords of
the <A HREF = "run.html">run</A> command.
</P>
<P>The forces due to this fix are imposed during an energy minimization,
invoked by the <A HREF = "minimize.html">minimize</A> command.
</P>
<P>IMPORTANT NOTE: If you want the atom/wall interaction energy to be
included in the total potential energy of the system (the quantity
being minimized), you MUST enable the <A HREF = "fix_modify.html">fix_modify</A>
<I>energy</I> option for this fix.
</P>
<P><B>Restrictions:</B>
</P>
<P>Any dimension (xyz) that has a LJ 9/3 wall must be non-periodic.
</P>
<P><B>Related commands:</B>
</P>
<P><A HREF = "fix_wall_reflect.html">fix wall/reflect</A>, <A HREF = "fix_wall_lj126.html">fix
wall/lj126</A>
</P>
<P><B>Default:</B> none
</P>
</HTML>
Event Timeline
Log In to Comment