"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)

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fix filter/corotate command :h3

[Syntax:]

fix ID group-ID filter/corotate keyword value ... :pre

ID, group-ID are documented in "fix"_fix.html command :ulb,l
one or more constraint/value pairs are appended :l
constraint = {b} or {a} or {t} or {m} :l
  {b} values = one or more bond types
  {a} values = one or more angle types
  {t} values = one or more atom types
  {m} value = one or more mass values :pre
:ule

[Examples:]

timestep 8
run_style respa 3 2 8 bond 1 pair 2 kspace 3
fix cor all filter/corotate m 1.0 :pre

fix cor all filter/corotate b 4 19 a 3 5 2 :pre

[Description:]

This fix implements a corotational filter for a mollified impulse
method. In biomolecular simulations, it allows the usage of larger
timesteps for long-range electrostatic interactions.  For details, see
"(Fath)"_#Fath2017.

When using "run_style respa"_run_style.html for a biomolecular
simulation with high-frequency covalent bonds, the outer time-step is
restricted to below ~ 4fs due to resonance problems. This fix filters
the outer stage of the respa and thus a larger (outer) time-step can
be used. Since in large biomolecular simulations the computation of
the long-range electrostatic contributions poses a major bottleneck,
this can significantly accelerate the simulation.

The filter computes a cluster decomposition of the molecular structure
following the criteria indicated by the options a, b, t and m. This
process is similar to the approach in "fix shake"_fix_shake.html,
however, the clusters are not kept contrained. Instead, the position
is slightly modified only for the computation of long-range forces. A
good cluster decomposition constitutes in building clusters which
contain the fastest covalent bonds inside clusters.

If the clusters are chosen suitably, the "run_style
respa"_run_style.html is stable for outer time-steps of at least 8fs.

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

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

[Restrictions:]

This fix is part of the USER-MISC package. It is only enabled if 
LAMMPS was built with that package. See the "Making 
LAMMPS"_Section_start.html#start_3 section for more info.

Currently, it does not support "molecule templates"_molecule.html.

[Related commands:]


[Default:] none

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:link(Fath2017)
[(Fath)] Fath, Hochbruck, Singh, J Comp Phys, 333, 180-198 (2017).
