91 lines
2.1 KiB
ReStructuredText
91 lines
2.1 KiB
ReStructuredText
.. index:: pair_style harmonic/cut
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.. index:: pair_style harmonic/cut/omp
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pair_style harmonic/cut command
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===============================
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Accelerator Variants: *harmonic/cut/omp*
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Syntax
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""""""
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.. code-block:: LAMMPS
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pair_style style
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* style = *harmonic/cut*
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Examples
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""""""""
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.. code-block:: LAMMPS
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pair_style harmonic/cut
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pair_coeff * * 0.2 2.0
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pair_coeff 1 1 0.5 2.5
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Description
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"""""""""""
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Style *harmonic/cut* computes pairwise repulsive-only harmonic interactions with the formula
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.. math::
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E = k (r_c - r)^2 \qquad r < r_c
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:math:`r_c` is the cutoff.
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The following coefficients must be defined for each pair of atoms
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types via the :doc:`pair_coeff <pair_coeff>` command as in the examples
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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 units)
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* :math:`r_c` (distance units)
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----------
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.. include:: accel_styles.rst
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----------
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Mixing, shift, table, tail correction, restart, rRESPA info
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"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
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For atom type pairs I,J and I != J, the :math:`k` and :math:`r_c`
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coefficients can be mixed. The default mix value is *geometric*.
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See the "pair_modify" command for details.
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Since the potential is zero at and beyond the cutoff parameter by
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construction, there is no need to support the :doc:`pair_modify
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<pair_modify>` shift or tail options for the energy and pressure of the
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pair interaction.
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These pair styles write their information to :doc:`binary restart files <restart>`,
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so pair_style and pair_coeff commands do not need to be specified in an input script
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that reads a restart file.
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These pair styles can only be used via the *pair* keyword of the
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:doc:`run_style respa <run_style>` command. They do not support the
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*inner*, *middle*, *outer* keywords.
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----------
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Restrictions
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""""""""""""
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The *harmonic/cut* pair style is only enabled if LAMMPS was
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built with the EXTRA-PAIR package.
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See the :doc:`Build package <Build_package>` page for more info.
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Related commands
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""""""""""""""""
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:doc:`pair_coeff <pair_coeff>`
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Default
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"""""""
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none
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