.. index:: bond_style nonlinear

bond_style nonlinear command
============================

bond_style nonlinear/omp command
================================

Syntax
""""""

.. parsed-literal::

   bond_style nonlinear

Examples
""""""""

.. parsed-literal::

   bond_style nonlinear
   bond_coeff 2 100.0 1.1 1.4

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

The *nonlinear* bond style uses the potential

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

to define an anharmonic spring :ref:`(Rector) <Rector>` of equilibrium
length r0 and maximum extension lamda.

The following coefficients must be defined for each bond type via the
:doc:`bond_coeff <bond_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:

* epsilon (energy)
* r0 (distance)
* lamda (distance)


----------


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 bond style can only be used if LAMMPS was built with the
MOLECULE package (which it is by default).  See the :ref:`Making LAMMPS <start_3>` section for more info on packages.

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

:doc:`bond_coeff <bond_coeff>`, :doc:`delete_bonds <delete_bonds>`

**Default:** none


----------


.. _Rector:



**(Rector)** Rector, Van Swol, Henderson, Molecular Physics, 82, 1009 (1994).


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