110 lines
2.8 KiB
Plaintext
110 lines
2.8 KiB
Plaintext
.. index:: dihedral_style opls
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dihedral_style opls command
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===========================
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dihedral_style opls/intel command
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=================================
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dihedral_style opls/kk command
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==============================
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dihedral_style opls/omp command
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===============================
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Syntax
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""""""
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.. parsed-literal::
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dihedral_style opls
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Examples
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""""""""
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.. parsed-literal::
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dihedral_style opls
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dihedral_coeff 1 1.740 -0.157 0.279 0.00 # CT-CT-CT-CT
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dihedral_coeff 2 0.000 0.000 0.366 0.000 # CT-CT-CT-HC
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dihedral_coeff 3 0.000 0.000 0.318 0.000 # HC-CT-CT-HC
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Description
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"""""""""""
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The *opls* dihedral style uses the potential
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.. image:: Eqs/dihedral_opls.jpg
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:align: center
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Note that the usual 1/2 factor is not included in the K values.
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This dihedral potential is used in the OPLS force field and is
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described in :ref:`(Watkins) <Watkins>`.
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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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* K1 (energy)
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* K2 (energy)
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* K3 (energy)
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* K4 (energy)
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----------
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Styles with a *cuda*\ , *gpu*\ , *intel*\ , *kk*\ , *omp*\ , or *opt* suffix are
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functionally the same as the corresponding style without the suffix.
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They have been optimized to run faster, depending on your available
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hardware, as discussed in :doc:`Section_accelerate <Section_accelerate>`
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of the manual. The accelerated styles take the same arguments and
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should produce the same results, except for round-off and precision
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issues.
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These accelerated styles are part of the USER-CUDA, GPU, USER-INTEL,
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KOKKOS, USER-OMP and OPT packages, respectively. They are only
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enabled if LAMMPS was built with those packages. See the :ref:`Making LAMMPS <start_3>` section for more info.
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You can specify the accelerated styles explicitly in your input script
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by including their suffix, or you can use the :ref:`-suffix command-line switch <start_7>` when you invoke LAMMPS, or you can
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use the :doc:`suffix <suffix>` command in your input script.
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See :doc:`Section_accelerate <Section_accelerate>` of the manual for
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more instructions on how to use the accelerated styles effectively.
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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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MOLECULE package (which it is by default). See the :ref:`Making LAMMPS <start_3>` section for more info on packages.
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Related commands
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""""""""""""""""
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:doc:`dihedral_coeff <dihedral_coeff>`
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**Default:** none
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----------
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.. _Watkins:
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**(Watkins)** Watkins and Jorgensen, J Phys Chem A, 105, 4118-4125 (2001).
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.. _lws: http://lammps.sandia.gov
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.. _ld: Manual.html
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.. _lc: Section_commands.html#comm
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