Update docs: bond_class2

\documentclass[12pt]{article}

\begin{document}

$$

   E = K_2 (r - r_0)^2 + K_3 (r - r_0)^3 + K_4 (r - r_0)^4 

$$

\end{document}

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.. index:: bond\_style class2

.. index:: bond_style class2

bond\_style class2 command

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

bond_style class2 command

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

bond\_style class2/omp command

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

bond\_style class2/kk command

bond_style class2/omp command

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

bond_style class2/kk command

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

Syntax

""""""

.. parsed-literal::

.. code-block:: LAMMPS

   bond_style class2

""""""""

.. parsed-literal::

.. code-block:: LAMMPS

   bond_style class2

   bond_coeff 1 1.0 100.0 80.0 80.0

The *class2* bond style uses the potential

.. image:: Eqs/bond_class2.jpg

   :align: center

.. math::

   E = K_2 (r - r_0)^2 + K_3 (r - r_0)^3 + K_4 (r - r_0)^4

where r0 is the equilibrium bond distance.

where :math:`r_0` is the equilibrium bond distance.

See :ref:`(Sun) <bond-Sun>` for a description of the COMPASS class2 force field.

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

or :doc:`read\_restart <read_restart>` commands:

* R0 (distance)

* K2 (energy/distance\^2)

* K3 (energy/distance\^3)

* K4 (energy/distance\^4)

* :math:`r_0` (distance)

* :math:`K_2` (energy/distance\^2)

* :math:`K_3` (energy/distance\^3)

* :math:`K_4` (energy/distance\^4)

----------

**(Sun)** Sun, J Phys Chem B 102, 7338-7364 (1998).

.. _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

bond_style class2 command :h3

bond_style class2/omp command :h3

bond_style class2/kk command :h3

[Syntax:]

bond_style class2 :pre

[Examples:]

bond_style class2

bond_coeff 1 1.0 100.0 80.0 80.0 :pre

[Description:]

The {class2} bond style uses the potential

:c,image(Eqs/bond_class2.jpg)

where r0 is the equilibrium bond distance.

See "(Sun)"_#bond-Sun for a description of the COMPASS class2 force field.

The following coefficients must be defined for each bond type via the

"bond_coeff"_bond_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:

R0 (distance)

K2 (energy/distance^2)

K3 (energy/distance^3)

K4 (energy/distance^4) :ul

:line

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 "Speed packages"_Speed_packages.html 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 "Build

package"_Build_package.html 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 "-suffix command-line

switch"_Run_options.html when you invoke LAMMPS, or you can use the

"suffix"_suffix.html command in your input script.

See the "Speed packages"_Speed_packages.html doc page for more

instructions on how to use the accelerated styles effectively.

:line

[Restrictions:]

This bond style can only be used if LAMMPS was built with the CLASS2

package.  See the "Build package"_Build_package.html doc page for more

info.

[Related commands:]

"bond_coeff"_bond_coeff.html, "delete_bonds"_delete_bonds.html

[Default:] none

:line

:link(bond-Sun)

[(Sun)] Sun, J Phys Chem B 102, 7338-7364 (1998).