git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@14950 f3b2605a-c512-4ea7-a41b-209d697bcdaa

doc/html/_sources/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 *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