.. index:: dihedral_style nharmonic

dihedral_style nharmonic command
================================

dihedral_style nharmonic/omp command
====================================

Syntax
""""""

.. parsed-literal::

   dihedral_style nharmonic

Examples
""""""""

.. parsed-literal::

   dihedral_style nharmonic
   dihedral_coeff 3 10.0 20.0 30.0

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

The *nharmonic* dihedral style uses the potential:

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

The following coefficients must be defined for each dihedral type via the
:doc:`dihedral_coeff <dihedral_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:

* n (integer >=1)
* A1 (energy)
* A2 (energy)
* ...
* An (energy)


----------


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:`dihedral_coeff <dihedral_coeff>`

**Default:** none


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