108 lines
3.1 KiB
ReStructuredText
108 lines
3.1 KiB
ReStructuredText
.. index:: pair_style lj/smooth/linear
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.. index:: pair_style lj/smooth/linear/omp
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pair_style lj/smooth/linear command
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===================================
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Accelerator Variants: *lj/smooth/linear/omp*
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Syntax
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""""""
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.. code-block:: LAMMPS
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pair_style lj/smooth/linear cutoff
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* cutoff = global cutoff for Lennard-Jones interactions (distance units)
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Examples
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""""""""
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.. code-block:: LAMMPS
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pair_style lj/smooth/linear 2.5
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pair_coeff * * 1.0 1.0
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pair_coeff 1 1 0.3 3.0 9.0
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Description
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"""""""""""
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Style *lj/smooth/linear* computes a truncated and force-shifted LJ
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interaction (aka Shifted Force Lennard-Jones) that combines the
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standard 12/6 Lennard-Jones function and subtracts a linear term based
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on the cutoff distance, so that both, the potential and the force, go
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continuously to zero at the cutoff Rc :ref:`(Toxvaerd) <Toxvaerd>`:
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.. math::
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\phi\left(r\right) & = 4 \epsilon \left[ \left(\frac{\sigma}{r}\right)^{12} -
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\left(\frac{\sigma}{r}\right)^6 \right] \\
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E\left(r\right) & = \phi\left(r\right) - \phi\left(R_c\right) - \left(r - R_c\right) \left.\frac{d\phi}{d r} \right|_{r=R_c} \qquad r < R_c
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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, or by mixing as described below:
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* :math:`\epsilon` (energy units)
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* :math:`\sigma` (distance units)
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* cutoff (distance units)
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The last coefficient is optional. If not specified, the global
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LJ cutoff specified in the pair_style command is used.
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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 epsilon and sigma coefficients
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and cutoff distance can be mixed. The default mix value is geometric.
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See the "pair_modify" command for details.
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This pair style does not support the :doc:`pair_modify <pair_modify>`
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shift option for the energy of the pair interaction, since it goes
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to 0.0 at the cutoff by construction.
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The :doc:`pair_modify <pair_modify>` table option is not relevant
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for this pair style.
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This pair style does not support the :doc:`pair_modify <pair_modify>`
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tail option for adding long-range tail corrections to energy and
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pressure, since the energy of the pair interaction is smoothed to 0.0
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at the cutoff.
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This pair style writes its information to :doc:`binary restart files <restart>`, so pair_style and pair_coeff commands do not need
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to be specified in an input script that reads a restart file.
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This pair style can only be used via the *pair* keyword of the
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:doc:`run_style respa <run_style>` command. It does 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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none
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Related commands
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""""""""""""""""
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:doc:`pair_coeff <pair_coeff>`, :doc:`pair lj/smooth <pair_lj_smooth>`
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Default
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"""""""
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none
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----------
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.. _Toxvaerd:
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**(Toxvaerd)** Toxvaerd, Dyre, J Chem Phys, 134, 081102 (2011).
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