85 lines
2.2 KiB
ReStructuredText
85 lines
2.2 KiB
ReStructuredText
.. index:: pair_style momb
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pair_style momb command
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=======================
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Syntax
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""""""
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.. code-block:: LAMMPS
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pair_style momb cutoff s6 d
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* cutoff = global cutoff (distance units)
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* s6 = global scaling factor of the exchange-correlation functional used (unitless)
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* d = damping scaling factor of Grimme's method (unitless)
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Examples
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""""""""
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.. code-block:: LAMMPS
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pair_style momb 12.0 0.75 20.0
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pair_style hybrid/overlay eam/fs lj/charmm/coul/long 10.0 12.0 momb 12.0 0.75 20.0 morse 5.5
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pair_coeff 1 2 momb 0.0 1.0 1.0 10.2847 2.361
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Description
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"""""""""""
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Style *momb* computes pairwise van der Waals (vdW) and short-range
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interactions using the Morse potential and :ref:`(Grimme) <Grimme>` method
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implemented in the Many-Body Metal-Organic (MOMB) force field
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described comprehensively in :ref:`(Fichthorn) <Fichthorn>` and
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:ref:`(Zhou) <Zhou5>`. Grimme's method is widely used to correct for
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dispersion in density functional theory calculations.
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.. math::
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E & = D_0 [\exp^{-2 \alpha (r-r_0)} - 2\exp^{-\alpha (r-r_0)}] - s_6 \frac{C_6}{r^6} f_{damp}(r,R_r) \\
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f_{damp}(r,R_r) & = \frac{1}{1 + \exp^{-d(r/R_r - 1)}}
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For the *momb* pair style, the following coefficients must be defined
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for each pair of atoms types via the :doc:`pair_coeff <pair_coeff>`
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command as in the examples above, or in the data file or restart files
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read by the :doc:`read_data <read_data>` as described below:
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* :math:`D_0` (energy units)
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* :math:`\alpha` (1/distance units)
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* :math:`r_0` (distance units)
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* :math:`C_6` (energy\*distance\^6 units)
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* :math:`R_r` (distance units, typically sum of atomic vdW radii)
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----------
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Restrictions
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""""""""""""
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This style is part of the EXTRA-PAIR package. It is only enabled if
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LAMMPS is built with that package. See the :doc:`Build package
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<Build_package>` page on for more info.
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Related commands
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""""""""""""""""
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:doc:`pair_coeff <pair_coeff>`, :doc:`pair_style morse <pair_morse>`
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Default
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"""""""
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none
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----------
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.. _Grimme:
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**(Grimme)** Grimme, J Comput Chem, 27(15), 1787-1799 (2006).
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.. _Fichthorn:
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**(Fichthorn)** Fichthorn, Balankura, Qi, CrystEngComm, 18(29), 5410-5417 (2016).
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.. _Zhou5:
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**(Zhou)** Zhou, Saidi, Fichthorn, J Phys Chem C, 118(6), 3366-3374 (2014).
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