forked from lijiext/lammps
71 lines
1.7 KiB
Plaintext
71 lines
1.7 KiB
Plaintext
.. index:: angle_style sdk
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angle_style sdk command
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=======================
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Syntax
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""""""
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.. parsed-literal::
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angle_style sdk
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.. parsed-literal::
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angle_style sdk/omp
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Examples
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""""""""
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.. parsed-literal::
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angle_style sdk
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angle_coeff 1 300.0 107.0
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Description
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"""""""""""
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The *sdk* angle style is a combination of the harmonic angle potential,
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.. image:: Eqs/angle_harmonic.jpg
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:align: center
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where theta0 is the equilibrium value of the angle and K a prefactor,
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with the *repulsive* part of the non-bonded *lj/sdk* pair style
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between the atoms 1 and 3. This angle potential is intended for
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coarse grained MD simulations with the CMM parametrization using the
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:doc:`pair_style lj/sdk <pair_sdk>`. Relative to the pair_style
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*lj/sdk*, however, the energy is shifted by *epsilon*, to avoid sudden
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jumps. Note that the usual 1/2 factor is included in K.
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The following coefficients must be defined for each angle type via the
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:doc:`angle_coeff <angle_coeff>` command as in the example above:
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* K (energy/radian^2)
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* theta0 (degrees)
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Theta0 is specified in degrees, but LAMMPS converts it to radians
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internally; hence the units of K are in energy/radian^2.
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The also required *lj/sdk* parameters will be extracted automatically
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from the pair_style.
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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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USER-CG-CMM package. 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:`angle_coeff <angle_coeff>`, :doc:`angle_style harmonic <angle_harmonic>`, :doc:`pair_style lj/sdk <pair_sdk>`,
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:doc:`pair_style lj/sdk/coul/long <pair_sdk>`
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**Default:** none
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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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