.. index:: angle_style fourier

angle_style fourier command
===========================

angle_style fourier/omp command
===============================

Syntax
""""""


.. code-block:: LAMMPS

   angle_style fourier

Examples
""""""""

.. code-block:: LAMMPS

   angle_style fourier
   angle_coeff 75.0 1.0 1.0 1.0

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

The *fourier* angle style uses the potential

.. math::

   E = K [C_0 + C_1 \cos ( \theta) + C_2 \cos( 2 \theta) ]


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:

* :math:`K` (energy)
* :math:`C_0` (real)
* :math:`C_1` (real)
* :math:`C_2` (real)


----------


Styles with a *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 on the :doc:`Speed packages <Speed_packages>` doc
page.  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 GPU, USER-INTEL, KOKKOS,
USER-OMP and OPT packages, respectively.  They are only enabled if
LAMMPS was built with those packages.  See the :doc:`Build package <Build_package>` doc page for more info.

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

See the :doc:`Speed packages <Speed_packages>` doc page 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 :doc:`Build package <Build_package>` doc
page for more info.

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

:doc:`angle\_coeff <angle_coeff>`

**Default:** none
