forked from lijiext/lammps
95 lines
3.3 KiB
Plaintext
95 lines
3.3 KiB
Plaintext
"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
|
|
|
|
improper_style command :h3
|
|
|
|
[Syntax:]
|
|
|
|
improper_style style :pre
|
|
|
|
style = {none} or {hybrid} or {class2} or {cvff} or {harmonic} :ul
|
|
|
|
[Examples:]
|
|
|
|
improper_style harmonic
|
|
improper_style cvff
|
|
improper_style hybrid cvff harmonic :pre
|
|
|
|
[Description:]
|
|
|
|
Set the formula(s) LAMMPS uses to compute improper interactions
|
|
between quadruplets of atoms, which remain in force for the duration
|
|
of the simulation. The list of improper quadruplets is read in by a
|
|
"read_data"_read_data.html or "read_restart"_read_restart.html command
|
|
from a data or restart file. Note that the ordering of the 4 atoms in
|
|
an improper quadruplet determines the the definition of the improper
|
|
angle used in the formula for each style. See the doc pages of
|
|
individual styles for details.
|
|
|
|
Hybrid models where impropers are computed using different improper
|
|
potentials can be setup using the {hybrid} improper style.
|
|
|
|
The coefficients associated with an improper style can be specified in
|
|
a data or restart file or via the "improper_coeff"_improper_coeff.html
|
|
command.
|
|
|
|
All improper potentials store their coefficient data in binary restart
|
|
files which means improper_style and
|
|
"improper_coeff"_improper_coeff.html commands do not need to be
|
|
re-specified in an input script that restarts a simulation. See the
|
|
"read_restart"_read_restart.html command for details on how to do
|
|
this. The one exception is that improper_style {hybrid} only stores
|
|
the list of sub-styles in the restart file; improper coefficients need
|
|
to be re-specified.
|
|
|
|
IMPORTANT NOTE: When both an improper and pair style is defined, the
|
|
"special_bonds"_special_bonds.html command often needs to be used to
|
|
turn off (or weight) the pairwise interaction that would otherwise
|
|
exist between a group of 4 bonded atoms.
|
|
|
|
:line
|
|
|
|
Here is an alphabetic list of improper styles defined in LAMMPS.
|
|
Click on the style to display the formula it computes and coefficients
|
|
specified by the associated "improper_coeff"_improper_coeff.html
|
|
command.
|
|
|
|
Note that there are also additional improper styles submitted by users
|
|
which are included in the LAMMPS distribution. The list of these with
|
|
links to the individual styles are given in the improper section of
|
|
"this page"_Section_commands.html#cmd_5.
|
|
|
|
"improper_style none"_improper_none.html - turn off improper interactions
|
|
"improper_style hybrid"_improper_hybrid.html - define multiple styles of improper interactions :ul
|
|
|
|
"improper_style class2"_improper_class2.html - COMPASS (class 2) improper
|
|
"improper_style cvff"_improper_cvff.html - CVFF improper
|
|
"improper_style harmonic"_improper_harmonic.html - harmonic improper
|
|
"improper_style umbrella"_improper_umbrella.html - DREIDING improper :ul
|
|
|
|
:line
|
|
|
|
[Restrictions:]
|
|
|
|
Improper styles can only be set for atom_style choices that allow
|
|
impropers to be defined.
|
|
|
|
Most improper styles are part of the MOLECULAR package. They are only
|
|
enabled if LAMMPS was built with that package. See the "Making
|
|
LAMMPS"_Section_start.html#start_3 section for more info on packages.
|
|
The doc pages for individual improper potentials tell if it is part of
|
|
a package.
|
|
|
|
[Related commands:]
|
|
|
|
"improper_coeff"_improper_coeff.html
|
|
|
|
[Default:]
|
|
|
|
improper_style none :pre
|