110 lines
3.6 KiB
ReStructuredText
110 lines
3.6 KiB
ReStructuredText
.. index:: pair_style lebedeva/z
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pair_style lebedeva/z 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 [hybrid/overlay ...] lebedeva/z cutoff
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Examples
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""""""""
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.. code-block:: LAMMPS
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pair_style hybrid/overlay lebedeva/z 20.0
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pair_coeff * * none
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pair_coeff 1 2 lebedeva/z CC.Lebedeva C C
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pair_style hybrid/overlay rebo lebedeva/z 14.0
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pair_coeff * * rebo CH.rebo C C
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pair_coeff 1 2 lebedeva/z CC.Lebedeva C C
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Description
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"""""""""""
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The *lebedeva/z* pair style computes the Lebedeva interaction potential
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as described in :ref:`(Lebedeva1) <Leb01>` and :ref:`(Lebedeva2)
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<Leb02>`. An important simplification is made, which is to take all
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normals along the z-axis.
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The Lebedeva potential is intended for the description of the interlayer
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interaction between graphene layers. To perform a realistic simulation,
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this potential must be used in combination with an intralayer potential
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such as :doc:`AIREBO <pair_airebo>` or :doc:`Tersoff <pair_tersoff>`
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facilitated by using pair style :doc:`hybrid/overlay <pair_hybrid>`. To
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keep the intralayer properties unaffected, the interlayer interaction
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within the same layers should be avoided. This can be achieved by
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assigning different atom types to atoms of different layers (e.g. 1 and
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2 in the examples above).
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Other interactions can be set to zero using pair_style *none*\ .
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.. math::
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E = & \frac{1}{2} \sum_i \sum_{j \neq i} V_{ij}\\
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V_{ij} = & B e^{-\alpha(r_{ij} - z_0)} \\
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& + C(1 + D_1\rho^2_{ij} + D_2\rho^4_{ij}) e^{-\lambda_1\rho^2_{ij}} e^{-\lambda_2 (z^2_{ij} - z^2_0)} \\
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& - A \left(\frac{z_0}{r_ij}\right)^6 + A \left( \frac{z_0}{r_c} \right)^6 \\
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\rho^2_{ij} = & x^2_{ij} + y^2_{ij} \qquad (\mathbf{n_i} \equiv \mathbf{\hat{z}})
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It is important to have a sufficiently large cutoff to ensure smooth forces.
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Energies are shifted so that they go continuously to zero at the cutoff assuming
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that the exponential part of :math:`V_{ij}` (first term) decays sufficiently fast.
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This shift is achieved by the last term in the equation for :math:`V_{ij}` above.
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The provided parameter file (CC.Lebedeva) contains two sets of parameters.
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- The first set (element name "C") is suitable for normal conditions and
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is taken from :ref:`(Popov1) <Popov>`
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- The second set (element name "C1") is suitable for high-pressure
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conditions and is taken from :ref:`(Koziol1) <Koziol>`
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Both sets contain an additional parameter, *S*, that can be used to
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facilitate scaling of energies and is set to 1.0 by default.
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Restrictions
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""""""""""""
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This pair style is part of the INTERLAYER package. It is only enabled
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if LAMMPS was built with that package. See the :doc:`Build package
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<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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:doc:`pair_style none <pair_none>`,
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:doc:`pair_style hybrid/overlay <pair_hybrid>`,
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:doc:`pair_style drip <pair_drip>`,
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:doc:`pair_style ilp/graphene/hbd <pair_ilp_graphene_hbn>`,
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:doc:`pair_style kolmogorov/crespi/z <pair_kolmogorov_crespi_z>`,
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:doc:`pair_style kolmogorov/crespi/full <pair_kolmogorov_crespi_full>`.
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Default
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"""""""
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none
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----------
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.. _Leb01:
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**(Lebedeva1)** I. V. Lebedeva, A. A. Knizhnik, A. M. Popov, Y. E. Lozovik, B. V. Potapkin, Phys. Rev. B, 84, 245437 (2011)
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.. _Leb02:
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**(Lebedeva2)** I. V. Lebedeva, A. A. Knizhnik, A. M. Popov, Y. E. Lozovik, B. V. Potapkin, Physica E: 44, 949-954 (2012)
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.. _Popov:
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**(Popov1)** A.M. Popov, I. V. Lebedeva, A. A. Knizhnik, Y. E. Lozovik and B. V. Potapkin, Chem. Phys. Lett. 536, 82-86 (2012).
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.. _Koziol:
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**(Koziol1)** Z. Koziol, G. Gawlik and J. Jagielski, Chinese Phys. B 28, 096101 (2019).
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