113 lines
4.0 KiB
ReStructuredText
113 lines
4.0 KiB
ReStructuredText
.. index:: pair_style quip
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pair_style quip 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 quip
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Examples
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""""""""
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.. code-block:: LAMMPS
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pair_style quip
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pair_coeff * * gap_example.xml "Potential xml_label=GAP_2014_5_8_60_17_10_38_466" 14
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pair_coeff * * sw_example.xml "IP SW" 14
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Description
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"""""""""""
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Style *quip* provides an interface for calling potential routines from
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the QUIP package. QUIP is built separately, and then linked to
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LAMMPS. The most recent version of the QUIP package can be downloaded
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from GitHub:
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`https://github.com/libAtoms/QUIP <https://github.com/libAtoms/QUIP>`_. The
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interface is chiefly intended to be used to run Gaussian Approximation
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Potentials (GAP), which are described in the following publications:
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:ref:`(Bartok et al) <Bartok_2010>` and :ref:`(PhD thesis of Bartok) <Bartok_PhD>`.
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Only a single pair_coeff command is used with the *quip* style that
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specifies a QUIP potential file containing the parameters of the
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potential for all needed elements in XML format. This is followed by a
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QUIP initialization string. Finally, the QUIP elements are mapped to
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LAMMPS atom types by specifying N atomic numbers, where N is the
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number of LAMMPS atom types:
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* QUIP filename
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* QUIP initialization string
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* N atomic numbers = mapping of QUIP elements to atom types
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See the :doc:`pair_coeff <pair_coeff>` page for alternate ways
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to specify the path for the potential file.
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A QUIP potential is fully specified by the filename which contains the
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parameters of the potential in XML format, the initialization string,
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and the map of atomic numbers.
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GAP potentials can be obtained from the `GAP models and databases page
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on the libAtoms homepage `https://libatoms.github.io
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<https://libatoms.github.io/GAP/data.html>`_, where the appropriate
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initialization strings are also advised. The list of atomic numbers must
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be matched to the LAMMPS atom types specified in the LAMMPS data file or
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elsewhere.
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Two examples input scripts are provided in the examples/PACKAGES/quip
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directory.
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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 :doc:`pair_modify <pair_modify>`
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mix, shift, table, and tail options.
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This pair style does not write its information to :doc:`binary restart files <restart>`, since it is stored in potential files. Thus, you
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need to re-specify the pair_style and pair_coeff commands in an input
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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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Restrictions
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""""""""""""
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This pair style is part of the ML-QUIP package. It is only enabled
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if LAMMPS was built with that package. See the :doc:`Build package <Build_package>` page for more info.
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QUIP potentials are parameterized in electron-volts and Angstroms and
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therefore should be used with LAMMPS metal :doc:`units <units>`.
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QUIP potentials are generally not designed to work with the scaling
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factors set by the :doc:`special_bonds <special_bonds>` command. The
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recommended setting in molecular systems is to include all
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interactions, i.e. to use *special_bonds lj/coul 1.0 1.0 1.0*. Scaling
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factors > 0.0 will be ignored and treated as 1.0. The only exception
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to this rule is if you know that your QUIP potential needs to exclude
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bonded, 1-3, or 1-4 interactions and does not already do this exclusion
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within QUIP. Then a factor 0.0 needs to be used which will remove such
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pairs from the neighbor list. This needs to be very carefully tested,
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because it may remove pairs from the neighbor list that are still
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required.
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Related commands
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""""""""""""""""
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:doc:`pair_coeff <pair_coeff>`
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----------
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.. _Bartok_2010:
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**(Bartok_2010)** AP Bartok, MC Payne, R Kondor, and G Csanyi, Physical
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Review Letters 104, 136403 (2010).
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.. _Bartok_PhD:
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**(Bartok_PhD)** A Bartok-Partay, PhD Thesis, University of Cambridge,
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(2010).
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