forked from lijiext/lammps
243 lines
7.7 KiB
Plaintext
243 lines
7.7 KiB
Plaintext
.. index:: pair_style born
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pair_style born command
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=======================
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pair_style born/omp command
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===========================
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pair_style born/gpu command
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===========================
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pair_style born/coul/long command
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=================================
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pair_style born/coul/long/cs command
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====================================
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pair_style born/coul/long/cuda command
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======================================
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pair_style born/coul/long/gpu command
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=====================================
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pair_style born/coul/long/omp command
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=====================================
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pair_style born/coul/msm command
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================================
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pair_style born/coul/msm/omp command
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====================================
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pair_style born/coul/wolf command
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=================================
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pair_style born/coul/wolf/gpu command
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=====================================
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pair_style born/coul/wolf/omp command
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=====================================
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Syntax
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""""""
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.. parsed-literal::
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pair_style style args
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* style = *born* or *born/coul/long* or *born/coul/long/cs* or *born/coul/msm* or *born/coul/wolf*
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* args = list of arguments for a particular style
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.. parsed-literal::
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*born* args = cutoff
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cutoff = global cutoff for non-Coulombic interactions (distance units)
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*born/coul/long* or *born/coul/long/cs* args = cutoff (cutoff2)
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cutoff = global cutoff for non-Coulombic (and Coulombic if only 1 arg) (distance units)
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cutoff2 = global cutoff for Coulombic (optional) (distance units)
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*born/coul/msm* args = cutoff (cutoff2)
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cutoff = global cutoff for non-Coulombic (and Coulombic if only 1 arg) (distance units)
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cutoff2 = global cutoff for Coulombic (optional) (distance units)
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*born/coul/wolf* args = alpha cutoff (cutoff2)
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alpha = damping parameter (inverse distance units)
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cutoff = global cutoff for non-Coulombic (and Coulombic if only 1 arg) (distance units)
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cutoff2 = global cutoff for Coulombic (optional) (distance units)
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Examples
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""""""""
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.. parsed-literal::
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pair_style born 10.0
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pair_coeff * * 6.08 0.317 2.340 24.18 11.51
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pair_coeff 1 1 6.08 0.317 2.340 24.18 11.51
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.. parsed-literal::
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pair_style born/coul/long 10.0
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pair_style born/coul/long/cs 10.0
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pair_style born/coul/long 10.0 8.0
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pair_style born/coul/long/cs 10.0 8.0
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pair_coeff * * 6.08 0.317 2.340 24.18 11.51
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pair_coeff 1 1 6.08 0.317 2.340 24.18 11.51
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.. parsed-literal::
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pair_style born/coul/msm 10.0
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pair_style born/coul/msm 10.0 8.0
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pair_coeff * * 6.08 0.317 2.340 24.18 11.51
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pair_coeff 1 1 6.08 0.317 2.340 24.18 11.51
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.. parsed-literal::
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pair_style born/coul/wolf 0.25 10.0
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pair_style born/coul/wolf 0.25 10.0 9.0
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pair_coeff * * 6.08 0.317 2.340 24.18 11.51
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pair_coeff 1 1 6.08 0.317 2.340 24.18 11.51
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Description
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"""""""""""
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The *born* style computes the Born-Mayer-Huggins or Tosi/Fumi
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potential described in :ref:`(Fumi and Tosi) <FumiTosi>`, given by
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.. image:: Eqs/pair_born.jpg
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:align: center
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where sigma is an interaction-dependent length parameter, rho is an
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ionic-pair dependent length parameter, and Rc is the cutoff.
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The styles with *coul/long* or *coul/msm* add a Coulombic term as
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described for the :doc:`lj/cut <pair_lj>` pair styles. An additional
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damping factor is applied to the Coulombic term so it can be used in
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conjunction with the :doc:`kspace_style <kspace_style>` command and its
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*ewald* or *pppm* of *msm* option. The Coulombic cutoff specified for
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this style means that pairwise interactions within this distance are
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computed directly; interactions outside that distance are computed in
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reciprocal space.
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If one cutoff is specified for the *born/coul/long* and
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*born/coul/msm* style, it is used for both the A,C,D and Coulombic
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terms. If two cutoffs are specified, the first is used as the cutoff
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for the A,C,D terms, and the second is the cutoff for the Coulombic
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term.
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The *born/coul/wolf* style adds a Coulombic term as described for the
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Wolf potential in the :doc:`coul/wolf <pair_coul>` pair style.
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Style *born/coul/long/cs* is identical to *born/coul/long* except that
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a term is added for the :ref:`core/shell model <howto_25>`
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to allow charges on core and shell particles to be separated by r =
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0.0.
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Note that these potentials are related to the :doc:`Buckingham potential <pair_buck>`.
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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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* A (energy units)
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* rho (distance units)
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* sigma (distance units)
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* C (energy units * distance units^6)
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* D (energy units * distance units^8)
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* cutoff (distance units)
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The second coefficient, rho, must be greater than zero.
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The last coefficient is optional. If not specified, the global A,C,D
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cutoff specified in the pair_style command is used.
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For *born/coul/long* and *born/coul/wolf* no Coulombic cutoff can be
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specified for an individual I,J type pair. All type pairs use the
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same global Coulombic cutoff specified in the pair_style command.
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----------
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Styles with a *cuda*, *gpu*, *intel*, *kk*, *omp*, or *opt* suffix are
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functionally the same as the corresponding style without the suffix.
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They have been optimized to run faster, depending on your available
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hardware, as discussed in :doc:`Section_accelerate <Section_accelerate>`
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of the manual. The accelerated styles take the same arguments and
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should produce the same results, except for round-off and precision
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issues.
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These accelerated styles are part of the USER-CUDA, GPU, USER-INTEL,
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KOKKOS, USER-OMP and OPT packages, respectively. They are only
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enabled if LAMMPS was built with those packages. See the :ref:`Making LAMMPS <start_3>` section for more info.
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You can specify the accelerated styles explicitly in your input script
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by including their suffix, or you can use the :ref:`-suffix command-line switch <start_7>` when you invoke LAMMPS, or you can
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use the :doc:`suffix <suffix>` command in your input script.
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See :doc:`Section_accelerate <Section_accelerate>` of the manual for
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more instructions on how to use the accelerated styles effectively.
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----------
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**Mixing, shift, table, tail correction, restart, rRESPA info**:
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These pair styles do not support mixing. Thus, coefficients for all
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I,J pairs must be specified explicitly.
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These styles support the :doc:`pair_modify <pair_modify>` shift option
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for the energy of the exp(), 1/r^6, and 1/r^8 portion of the pair
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interaction.
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The *born/coul/long* pair style supports the
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:doc:`pair_modify <pair_modify>` table option ti tabulate the
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short-range portion of the long-range Coulombic interaction.
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These styles support the pair_modify tail option for adding long-range
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tail corrections to energy and pressure.
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Thess styles writes thei information to binary :doc:`restart <restart>`
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files, so pair_style and pair_coeff commands do not need to be
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specified in an input script that reads a restart file.
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These styles can only be used via the *pair* keyword of the :doc:`run_style respa <run_style>` command. They do not support the *inner*,
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*middle*, *outer* keywords.
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----------
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Restrictions
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""""""""""""
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The *born/coul/long* style is part of the KSPACE package. It is only
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enabled if LAMMPS was built with that package (which it is by
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default). See the :ref:`Making LAMMPS <start_3>` section
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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 buck <pair_buck>`
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**Default:** none
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----------
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.. _FumiTosi:
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Fumi and Tosi, J Phys Chem Solids, 25, 31 (1964),
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Fumi and Tosi, J Phys Chem Solids, 25, 45 (1964).
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.. _lws: http://lammps.sandia.gov
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.. _ld: Manual.html
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.. _lc: Section_commands.html#comm
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