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rLAMMPS lammps
bond_fene.html
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<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>
bond_style fene command
</H3>
<H3>
bond_style fene/omp command
</H3>
<P><B>
Syntax:
</B>
</P>
<PRE>
bond_style fene
</PRE>
<P><B>
Examples:
</B>
</P>
<PRE>
bond_style fene
bond_coeff 1 30.0 1.5 1.0 1.0
</PRE>
<P><B>
Description:
</B>
</P>
<P>
The
<I>
fene
</I>
bond style uses the potential
</P>
<CENTER><IMG
SRC =
"Eqs/bond_fene.jpg"
>
</CENTER>
<P>
to define a finite extensible nonlinear elastic (FENE) potential
<A
HREF =
"#Kremer"
>
(Kremer)
</A>
, used for bead-spring polymer models. The first
term is attractive, the 2nd Lennard-Jones term is repulsive. The
first term extends to R0, the maximum extent of the bond. The 2nd
term is cutoff at 2^(1/6) sigma, the minimum of the LJ potential.
</P>
<P>
The following coefficients must be defined for each bond type via the
<A
HREF =
"bond_coeff.html"
>
bond_coeff
</A>
command as in the example above, or in
the data file or restart files read by the
<A
HREF =
"read_data.html"
>
read_data
</A>
or
<A
HREF =
"read_restart.html"
>
read_restart
</A>
commands:
</P>
<UL><LI>
K (energy/distance^2)
<LI>
R0 (distance)
<LI>
epsilon (energy)
<LI>
sigma (distance)
</UL>
<HR>
<P>
Styles with a
<I>
cuda
</I>
,
<I>
gpu
</I>
,
<I>
omp
</I>
, or
<I>
opt
</I>
suffix are functionally
the same as the corresponding style without the suffix. They have
been optimized to run faster, depending on your available hardware,
as discussed in
<A
HREF =
"Section_accelerate.html"
>
this section
</A>
of the manual.
The accelerated styles take the same arguments and should produce the
same results, except for round-off and precision issues.
</P>
<P>
These accelerated styles are part of the USER-CUDA, GPU, USER-OMP and OPT
packages, respectively. They are only enabled if LAMMPS was built with
those packages. See the
<A
HREF =
"Section_start.html#start_3"
>
Making LAMMPS
</A>
section for more info.
</P>
<P>
You can specify the accelerated styles explicitly in your input script
by including their suffix, or you can use the
<A
HREF =
"Section_start.html#start_6"
>
-suffix command-line
switch
</A>
when you invoke LAMMPS, or you can
use the
<A
HREF =
"suffix.html"
>
suffix
</A>
command in your input script.
</P>
<P>
See
<A
HREF =
"Section_accelerate.html"
>
this section
</A>
of the manual for more
instructions on how to use the accelerated styles effectively.
</P>
<HR>
<P><B>
Restrictions:
</B>
</P>
<P>
This bond style can only be used if LAMMPS was built with the
MOLECULAR package (which it is by default). See the
<A
HREF =
"Section_start.html#start_3"
>
Making
LAMMPS
</A>
section for more info on packages.
</P>
<P>
You typically should specify
<A
HREF =
"special_bonds.html"
"
>
special_bonds fene
</A>
or
<A
HREF =
"special_bonds.html"
>
special_bonds lj/coul 0 1 1
</A>
to use this bond
style. LAMMPS will issue a warning it that's not the case.
</P>
<P><B>
Related commands:
</B>
</P>
<P><A
HREF =
"bond_coeff.html"
>
bond_coeff
</A>
,
<A
HREF =
"delete_bonds.html"
>
delete_bonds
</A>
</P>
<P><B>
Default:
</B>
none
</P>
<HR>
<A
NAME =
"Kremer"
></A>
<P><B>
(Kremer)
</B>
Kremer, Grest, J Chem Phys, 92, 5057 (1990).
</P>
</HTML>
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