Update docs: angle_cosine_buck6d

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$$

  E = K \left[ 1 + \cos(n\theta - \theta_0)\right]

$$

\end{document}

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.. index:: angle\_style cosine/buck6d

.. index:: angle_style cosine/buck6d

angle\_style cosine/buck6d command

==================================

angle_style cosine/buck6d command

=================================

Syntax

""""""

.. parsed-literal::

.. code-block:: LAMMPS

   angle_style cosine/buck6d

""""""""

.. parsed-literal::

.. code-block:: LAMMPS

   angle_style cosine/buck6d

   angle_coeff 1  cosine/buck6d  1.978350  4  180.000000

The *cosine/buck6d* angle style uses the potential

.. image:: Eqs/angle_cosine_buck6d.jpg

   :align: center

.. math::

where K is the energy constant, n is the periodic multiplicity and

Theta0 is the equilibrium angle.

   E = K \left[ 1 + \cos(n\theta - \theta_0)\right]

where :math:`K` is the energy constant, :math:`n` is the periodic multiplicity and

:math:`\theta_0` is the equilibrium angle.

The coefficients must be defined for each angle type via the

:doc:`angle\_coeff <angle_coeff>` command as in the example above, or in

the data file or restart files read by the :doc:`read\_data <read_data>`

or :doc:`read\_restart <read_restart>` commands in the following order:

* K (energy)

* n

* Theta0 (degrees)

* :math:`K` (energy)

* :math:`n`

* :math:`\theta_0` (degrees)

Theta0 is specified in degrees, but LAMMPS converts it to radians

:math:`\theta_0` is specified in degrees, but LAMMPS converts it to radians

internally.

Additional to the cosine term the *cosine/buck6d* angle style computes

:doc:`angle\_coeff <angle_coeff>`

**Default:** none

.. _lws: http://lammps.sandia.gov

.. _ld: Manual.html

.. _lc: Commands_all.html

"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c

:link(lws,http://lammps.sandia.gov)

:link(ld,Manual.html)

:link(lc,Commands_all.html)

:line

angle_style cosine/buck6d command :h3

[Syntax:]

angle_style cosine/buck6d :pre

[Examples:]

angle_style cosine/buck6d

angle_coeff 1  cosine/buck6d  1.978350  4  180.000000 :pre

[Description:]

The {cosine/buck6d} angle style uses the potential

:c,image(Eqs/angle_cosine_buck6d.jpg)

where K is the energy constant, n is the periodic multiplicity and

Theta0 is the equilibrium angle.

The coefficients must be defined for each angle type via the

"angle_coeff"_angle_coeff.html command as in the example above, or in

the data file or restart files read by the "read_data"_read_data.html

or "read_restart"_read_restart.html commands in the following order:

K (energy)

n

Theta0 (degrees) :ul

Theta0 is specified in degrees, but LAMMPS converts it to radians

internally.

Additional to the cosine term the {cosine/buck6d} angle style computes

the short range (vdW) interaction belonging to the

"pair_buck6d"_pair_buck6d_coul_gauss.html between the end atoms of the

angle.  For this reason this angle style only works in combination

with the "pair_buck6d"_pair_buck6d_coul_gauss.html styles and needs

the "special_bonds"_special_bonds.html 1-3 interactions to be weighted

0.0 to prevent double counting.

:line

[Restrictions:]

{cosine/buck6d} can only be used in combination with the

"pair_buck6d"_pair_buck6d_coul_gauss.html style and with a

"special_bonds"_special_bonds.html 0.0 weighting of 1-3 interactions.

This angle style can only be used if LAMMPS was built with the

USER-MOFFF package.  See the "Build package"_Build_package.html doc

page for more info.

[Related commands:]

"angle_coeff"_angle_coeff.html

[Default:] none