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dihedral_quadratic.txt
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.. index:: dihedral_style quadratic
dihedral_style quadratic command
================================
dihedral_style quadratic/omp command
====================================
Syntax
""""""
.. parsed-literal::
dihedral_style quadratic
Examples
""""""""
.. parsed-literal::
dihedral_style quadratic
dihedral_coeff 100.0 80.0
Description
"""""""""""
The *quadratic* dihedral style uses the potential:
.. image:: Eqs/dihedral_quadratic.jpg
:align: center
This dihedral potential can be used to keep a dihedral in a predefined
value (cis=zero, right-hand convention is used).
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:
* K (energy/radian^2)
* phi0 (degrees)
----------
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 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 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
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