.. index:: angle_style cosine/shift

angle_style cosine/shift command
================================

angle_style cosine/shift/omp command
====================================

Syntax
""""""

.. parsed-literal::

   angle_style cosine/shift

Examples
""""""""

.. parsed-literal::

   angle_style cosine/shift
   angle_coeff * 10.0 45.0

Description
"""""""""""

The *cosine/shift* angle style uses the potential

.. image:: Eqs/angle_cosine_shift.jpg
   :align: center

where theta0 is the equilibrium angle. The potential is bounded
between -Umin and zero. In the neighborhood of the minimum E=- Umin +
Umin/4(theta-theta0)^2 hence the spring constant is umin/2.

The following 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:

* umin (energy)
* theta (angle)


----------


Styles with a *cuda*\ , *gpu*\ , *intel*\ , *kk*\ , *omp*\ , or *opt* 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 :doc:`Section_accelerate <Section_accelerate>`
of the manual.  The accelerated styles take the same arguments and
should produce the same results, except for round-off and precision
issues.

These accelerated styles are part of the USER-CUDA, GPU, USER-INTEL,
KOKKOS, USER-OMP and OPT packages, respectively.  They are only
enabled if LAMMPS was built with those packages.  See the :ref:`Making LAMMPS <start_3>` section for more info.

You can specify the accelerated styles explicitly in your input script
by including their suffix, or you can use the :ref:`-suffix command-line switch <start_7>` when you invoke LAMMPS, or you can
use the :doc:`suffix <suffix>` command in your input script.

See :doc:`Section_accelerate <Section_accelerate>` of the manual for
more instructions on how to use the accelerated styles effectively.


----------


Restrictions
""""""""""""


This angle style can only be used if LAMMPS was built with the
USER-MISC package.  See the :ref:`Making LAMMPS <start_3>`
section for more info on packages.

Related commands
""""""""""""""""

:doc:`angle_coeff <angle_coeff>`,
:doc:`angle_cosineshiftexp <angle_cosineshiftexp>`

**Default:** none


.. _lws: http://lammps.sandia.gov
.. _ld: Manual.html
.. _lc: Section_commands.html#comm