207 lines
7.9 KiB
ReStructuredText
207 lines
7.9 KiB
ReStructuredText
.. index:: pair_style ilp/graphene/hbn
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.. index:: pair_style ilp/graphene/hbn/opt
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pair_style ilp/graphene/hbn command
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===================================
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Accelerator Variant: *ilp/graphene/hbn/opt*
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Syntax
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""""""
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.. code-block:: LAMMPS
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pair_style [hybrid/overlay ...] ilp/graphene/hbn cutoff tap_flag
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* cutoff = global cutoff (distance units)
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* tap_flag = 0/1 to turn off/on the taper function
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Examples
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""""""""
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.. code-block:: LAMMPS
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pair_style hybrid/overlay ilp/graphene/hbn 16.0 1
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pair_coeff * * ilp/graphene/hbn BNCH.ILP B N C
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pair_style hybrid/overlay rebo tersoff ilp/graphene/hbn 16.0 coul/shield 16.0
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pair_coeff * * rebo CH.rebo NULL NULL C
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pair_coeff * * tersoff BNC.tersoff B N NULL
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pair_coeff * * ilp/graphene/hbn BNCH.ILP B N C
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pair_coeff 1 1 coul/shield 0.70
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pair_coeff 1 2 coul/shield 0.695
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pair_coeff 2 2 coul/shield 0.69
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Description
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"""""""""""
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The *ilp/graphene/hbn* style computes the registry-dependent interlayer
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potential (ILP) potential as described in :ref:`(Leven1) <Leven1>`,
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:ref:`(Leven2) <Leven2>` and :ref:`(Maaravi) <Maaravi2>`.
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The normals are calculated in the way as described
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in :ref:`(Kolmogorov) <Kolmogorov2>`.
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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} = & \mathrm{Tap}(r_{ij})\left \{ e^{-\alpha (r_{ij}/\beta -1)}
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\left [ \epsilon + f(\rho_{ij}) + f(\rho_{ji})\right ] -
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\frac{1}{1+e^{-d\left [ \left ( r_{ij}/\left (s_R \cdot r^{eff} \right ) \right )-1 \right ]}}
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\cdot \frac{C_6}{r^6_{ij}} \right \}\\
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\rho_{ij}^2 = & r_{ij}^2 - (\mathbf{r}_{ij} \cdot \mathbf{n}_i)^2 \\
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\rho_{ji}^2 = & r_{ij}^2 - (\mathbf{r}_{ij} \cdot \mathbf{n}_j)^2 \\
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f(\rho) = & C e^{ -( \rho / \delta )^2 } \\
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\mathrm{Tap}(r_{ij}) = & 20\left ( \frac{r_{ij}}{R_{cut}} \right )^7 -
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70\left ( \frac{r_{ij}}{R_{cut}} \right )^6 +
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84\left ( \frac{r_{ij}}{R_{cut}} \right )^5 -
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35\left ( \frac{r_{ij}}{R_{cut}} \right )^4 + 1
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Where :math:`\mathrm{Tap}(r_{ij})` is the taper function which provides
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a continuous cutoff (up to third derivative) for interatomic separations
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larger than :math:`r_c` :ref:`(Maaravi) <Maaravi2>`. The definitions of
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each parameter in the above equation can be found in :ref:`(Leven1)
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<Leven1>` and :ref:`(Maaravi) <Maaravi2>`.
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It is important to include all the pairs to build the neighbor list for
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calculating the normals.
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.. note::
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This potential (ILP) is intended for interlayer interactions between two
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different layers of graphene, hexagonal boron nitride (h-BN) and their hetero-junction.
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To perform a realistic simulation, this potential must be used in combination with
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intralayer potential, such as :doc:`AIREBO <pair_airebo>` or :doc:`Tersoff <pair_tersoff>` potential.
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To keep the intralayer properties unaffected, the interlayer interaction
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within the same layers should be avoided. Hence, each atom has to have a layer
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identifier such that atoms residing on the same layer interact via the
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appropriate intralayer potential and atoms residing on different layers
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interact via the ILP. Here, the molecule id is chosen as the layer identifier,
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thus a data file with the "full" atom style is required to use this potential.
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The parameter file (e.g. BNCH.ILP), is intended for use with *metal*
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:doc:`units <units>`, with energies in meV. Two additional parameters,
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*S*, and *rcut* are included in the parameter file. *S* is designed to
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facilitate scaling of energies. *rcut* is designed to build the neighbor
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list for calculating the normals for each atom pair.
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.. note::
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The parameters presented in the parameter file (e.g. BNCH.ILP),
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are fitted with taper function by setting the cutoff equal to 16.0
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Angstrom. Using different cutoff or taper function should be careful.
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The parameters for atoms pairs between Boron and Nitrogen are fitted with
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a screened Coulomb interaction :doc:`coul/shield <pair_coul_shield>`. Therefore,
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to simulated the properties of h-BN correctly, this potential must be used in
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combination with the pair style :doc:`coul/shield <pair_coul_shield>`.
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.. note::
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Four new sets of parameters of ILP for 2D layered Materials with bilayer and
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bulk configurations are presented in :ref:`(Ouyang1) <Ouyang1>` and :ref:`(Ouyang2) <Ouyang2>`, respectively.
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These parameters provide a good description in both short- and long-range interaction regimes.
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While the old ILP parameters published in :ref:`(Leven2) <Leven2>` and
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:ref:`(Maaravi) <Maaravi2>` are only suitable for long-range interaction
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regime. This feature is essential for simulations in high pressure
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regime (i.e., the interlayer distance is smaller than the equilibrium
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distance). The benchmark tests and comparison of these parameters can
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be found in :ref:`(Ouyang1) <Ouyang1>` and :ref:`(Ouyang2) <Ouyang2>`.
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This potential must be used in combination with hybrid/overlay.
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Other interactions can be set to zero using pair_style *none*\ .
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This pair style tallies a breakdown of the total interlayer potential
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energy into sub-categories, which can be accessed via the :doc:`compute pair <compute_pair>` command as a vector of values of length 2.
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The 2 values correspond to the following sub-categories:
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1. *E_vdW* = vdW (attractive) energy
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2. *E_Rep* = Repulsive energy
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To print these quantities to the log file (with descriptive column
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headings) the following commands could be included in an input script:
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.. code-block:: LAMMPS
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compute 0 all pair ilp/graphene/hbn
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variable Evdw equal c_0[1]
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variable Erep equal c_0[2]
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thermo_style custom step temp epair v_Erep v_Evdw
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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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This pair style does not support the pair_modify mix, shift, table, and
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tail options.
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This pair style does not write their information to binary restart
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files, since it is stored in potential files. Thus, you need to
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re-specify the pair_style and pair_coeff commands in an input script
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that reads a restart file.
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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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This pair style requires the newton setting to be *on* for pair
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interactions.
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The BNCH.ILP potential file provided with LAMMPS (see the potentials
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directory) are parameterized for *metal* units. You can use this
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potential with any LAMMPS units, but you would need to create your own
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custom BNCH.ILP potential file with coefficients listed in the appropriate
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units, if your simulation does not use *metal* units.
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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_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_tmd <pair_ilp_tmd>`,
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:doc:`pair_style saip_metal <pair_saip_metal>`,
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:doc:`pair_style pair_kolmogorov_crespi_z <pair_kolmogorov_crespi_z>`,
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:doc:`pair_style pair_kolmogorov_crespi_full <pair_kolmogorov_crespi_full>`,
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:doc:`pair_style pair_lebedeva_z <pair_lebedeva_z>`,
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:doc:`pair_style pair_coul_shield <pair_coul_shield>`.
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Default
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"""""""
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tap_flag = 1
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----------
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.. _Ouyang1:
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**(Ouyang1)** W. Ouyang, D. Mandelli, M. Urbakh and O. Hod, Nano Lett. 18, 6009-6016 (2018).
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.. _Ouyang2:
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**(Ouyang2)** W. Ouyang et al., J. Chem. Theory Comput. 16(1), 666-676 (2020).
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.. _Leven1:
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**(Leven1)** I. Leven, I. Azuri, L. Kronik and O. Hod, J. Chem. Phys. 140, 104106 (2014).
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.. _Leven2:
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**(Leven2)** I. Leven et al, J. Chem.Theory Comput. 12, 2896-905 (2016).
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.. _Maaravi2:
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**(Maaravi)** T. Maaravi et al, J. Phys. Chem. C 121, 22826-22835 (2017).
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.. _Kolmogorov2:
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**(Kolmogorov)** A. N. Kolmogorov, V. H. Crespi, Phys. Rev. B 71, 235415 (2005).
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