75 lines
1.5 KiB
ReStructuredText
75 lines
1.5 KiB
ReStructuredText
.. index:: improper_style fourier
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.. index:: improper_style fourier/omp
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improper_style fourier command
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==============================
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Accelerator Variants: *fourier/omp*
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Syntax
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""""""
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.. code-block:: LAMMPS
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improper_style fourier
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Examples
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""""""""
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.. code-block:: LAMMPS
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improper_style fourier
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improper_coeff 1 100.0 0.0 1.0 0.5 1
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Description
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"""""""""""
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The *fourier* improper style uses the following potential:
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.. math::
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E = K [C_0 + C_1 \cos ( \omega) + C_2 \cos( 2 \omega) ]
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where K is the force constant, C0, C1, C2 are dimensionless coefficients,
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and omega is the angle between the IL axis and the IJK plane:
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.. image:: JPG/umbrella.jpg
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:align: center
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If all parameter (see below) is not zero, the all the three possible angles will taken in account.
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The following coefficients must be defined for each improper type via
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the :doc:`improper_coeff <improper_coeff>` command as in the example
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above, or in the data file or restart files read by the
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:doc:`read_data <read_data>` or :doc:`read_restart <read_restart>`
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commands:
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* :math:`K` (energy)
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* :math:`C_0` (unitless)
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* :math:`C_1` (unitless)
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* :math:`C_2` (unitless)
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* all (0 or 1, optional)
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----------
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.. include:: accel_styles.rst
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----------
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Restrictions
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""""""""""""
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This angle 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>`
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doc page for more info.
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Related commands
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""""""""""""""""
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:doc:`improper_coeff <improper_coeff>`
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Default
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"""""""
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none
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