72 lines
1.5 KiB
ReStructuredText
72 lines
1.5 KiB
ReStructuredText
.. index:: dihedral_style cosine/squared/restricted
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dihedral_style cosine/squared/restricted command
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================================================
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Syntax
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""""""
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.. code-block:: LAMMPS
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dihedral_style cosine/squared/restricted
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Examples
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""""""""
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.. code-block:: LAMMPS
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dihedral_style cosine/squared/restricted
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dihedral_coeff 1 10.0 120
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Description
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"""""""""""
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.. versionadded:: 17Apr2024
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The *cosine/squared/restricted* dihedral style uses the potential
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.. math::
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E = K [\cos(\phi) - \cos(\phi_0)]^2 / \sin^2(\phi)
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, which is commonly used in the MARTINI force field.
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See :ref:`(Bulacu) <restricted-Bul>` for a description of the restricted dihedral for the MARTINI force field.
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The following coefficients must be defined for each dihedral type via the
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:doc:`dihedral_coeff <dihedral_coeff>` command as in the example above, or in
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the data file or restart files read by the :doc:`read_data <read_data>`
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or :doc:`read_restart <read_restart>` commands:
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* :math:`K` (energy)
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* :math:`\phi_0` (degrees)
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:math:`\phi_0` is specified in degrees, but LAMMPS converts it to radians internally.
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----------
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Restrictions
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""""""""""""
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This dihedral style can only be used if LAMMPS was built with the
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EXTRA-MOLECULE package. See the :doc:`Build package <Build_package>` doc page
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for more info.
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Related commands
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""""""""""""""""
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:doc:`dihedral_coeff <dihedral_coeff>`
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Default
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"""""""
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none
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----------
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.. _restricted-Bul:
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**(Bulacu)** Bulacu, Goga, Zhao, Rossi, Monticelli, Periole, Tieleman, Marrink, J Chem Theory Comput, 9, 3282-3292
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(2013).
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