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angle_sdk.txt
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.. index:: angle_style sdk
angle_style sdk command
=======================
Syntax
""""""
.. parsed-literal::
angle_style sdk
.. parsed-literal::
angle_style sdk/omp
Examples
""""""""
.. parsed-literal::
angle_style sdk
angle_coeff 1 300.0 107.0
Description
"""""""""""
The *sdk* angle style is a combination of the harmonic angle potential,
.. image:: Eqs/angle_harmonic.jpg
:align: center
where theta0 is the equilibrium value of the angle and K a prefactor,
with the *repulsive* part of the non-bonded *lj/sdk* pair style
between the atoms 1 and 3. This angle potential is intended for
coarse grained MD simulations with the CMM parametrization using the
:doc:`pair_style lj/sdk <pair_sdk>`. Relative to the pair_style
*lj/sdk*, however, the energy is shifted by *epsilon*, to avoid sudden
jumps. Note that the usual 1/2 factor is included in K.
The following coefficients must be defined for each angle type via the
:doc:`angle_coeff <angle_coeff>` command as in the example above:
* K (energy/radian^2)
* theta0 (degrees)
Theta0 is specified in degrees, but LAMMPS converts it to radians
internally; hence the units of K are in energy/radian^2.
The also required *lj/sdk* parameters will be extracted automatically
from the pair_style.
Restrictions
""""""""""""
This angle style can only be used if LAMMPS was built with the
USER-CG-CMM package. See the :ref:`Making LAMMPS <start_3>` section for more info on packages.
Related commands
""""""""""""""""
:doc:`angle_coeff <angle_coeff>`, :doc:`angle_style harmonic <angle_harmonic>`, :doc:`pair_style lj/sdk <pair_sdk>`,
:doc:`pair_style lj/sdk/coul/long <pair_sdk>`
**Default:** none
.. _lws: http://lammps.sandia.gov
.. _ld: Manual.html
.. _lc: Section_commands.html#comm
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