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angle_style.txt
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.. index:: angle_style
angle_style command
===================
Syntax
""""""
.. parsed-literal::
angle_style style
* style = *none* or *hybrid* or *charmm* or *class2* or *cosine* or *cosine/squared* or *harmonic*
Examples
""""""""
.. parsed-literal::
angle_style harmonic
angle_style charmm
angle_style hybrid harmonic cosine
Description
"""""""""""
Set the formula(s) LAMMPS uses to compute angle interactions between
triplets of atoms, which remain in force for the duration of the
simulation. The list of angle triplets is read in by a
:doc:`read_data <read_data>` or :doc:`read_restart <read_restart>` command
from a data or restart file.
Hybrid models where angles are computed using different angle
potentials can be setup using the *hybrid* angle style.
The coefficients associated with a angle style can be specified in a
data or restart file or via the :doc:`angle_coeff <angle_coeff>` command.
All angle potentials store their coefficient data in binary restart
files which means angle_style and :doc:`angle_coeff <angle_coeff>`
commands do not need to be re-specified in an input script that
restarts a simulation. See the :doc:`read_restart <read_restart>`
command for details on how to do this. The one exception is that
angle_style *hybrid* only stores the list of sub-styles in the restart
file; angle coefficients need to be re-specified.
.. note::
When both an angle and pair style is defined, the
:doc:`special_bonds <special_bonds>` command often needs to be used to
turn off (or weight) the pairwise interaction that would otherwise
exist between 3 bonded atoms.
In the formulas listed for each angle style, *theta* is the angle
between the 3 atoms in the angle.
----------
Here is an alphabetic list of angle styles defined in LAMMPS. Click on
the style to display the formula it computes and coefficients
specified by the associated :doc:`angle_coeff <angle_coeff>` command.
Note that there are also additional angle 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 angle section of :ref:`this page <cmd_5>`.
* :doc:`angle_style none <angle_none>` - turn off angle interactions
* :doc:`angle_style hybrid <angle_hybrid>` - define multiple styles of angle interactions
* :doc:`angle_style charmm <angle_charmm>` - CHARMM angle
* :doc:`angle_style class2 <angle_class2>` - COMPASS (class 2) angle
* :doc:`angle_style cosine <angle_cosine>` - cosine angle potential
* :doc:`angle_style cosine/delta <angle_cosine_delta>` - difference of cosines angle potential
* :doc:`angle_style cosine/periodic <angle_cosine_periodic>` - DREIDING angle
* :doc:`angle_style cosine/squared <angle_cosine_squared>` - cosine squared angle potential
* :doc:`angle_style harmonic <angle_harmonic>` - harmonic angle
* :doc:`angle_style table <angle_table>` - tabulated by angle
----------
Restrictions
""""""""""""
Angle styles can only be set for atom_styles that allow angles to be
defined.
Most angle styles are part of the MOLECULE package. They are only
enabled if LAMMPS was built with that package. See the :ref:`Making LAMMPS <start_3>` section for more info on packages.
The doc pages for individual bond potentials tell if it is part of a
package.
Related commands
""""""""""""""""
:doc:`angle_coeff <angle_coeff>`
Default
"""""""
.. parsed-literal::
angle_style none
.. _lws: http://lammps.sandia.gov
.. _ld: Manual.html
.. _lc: Section_commands.html#comm
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