forked from lijiext/lammps
250 lines
14 KiB
Plaintext
250 lines
14 KiB
Plaintext
.. index:: pair_style
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pair_style 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 = one of the styles from the list below
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* args = arguments used by a particular style
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Examples
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""""""""
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.. parsed-literal::
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pair_style lj/cut 2.5
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pair_style eam/alloy
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pair_style hybrid lj/charmm/coul/long 10.0 eam
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pair_style table linear 1000
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pair_style none
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Description
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"""""""""""
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Set the formula(s) LAMMPS uses to compute pairwise interactions. In
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LAMMPS, pair potentials are defined between pairs of atoms that are
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within a cutoff distance and the set of active interactions typically
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changes over time. See the :doc:`bond_style <bond_style>` command to
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define potentials between pairs of bonded atoms, which typically
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remain in place for the duration of a simulation.
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In LAMMPS, pairwise force fields encompass a variety of interactions,
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some of which include many-body effects, e.g. EAM, Stillinger-Weber,
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Tersoff, REBO potentials. They are still classified as "pairwise"
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potentials because the set of interacting atoms changes with time
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(unlike molecular bonds) and thus a neighbor list is used to find
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nearby interacting atoms.
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Hybrid models where specified pairs of atom types interact via
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different pair potentials can be setup using the *hybrid* pair style.
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The coefficients associated with a pair style are typically set for
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each pair of atom types, and are specified by the
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:doc:`pair_coeff <pair_coeff>` command or read from a file by the
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:doc:`read_data <read_data>` or :doc:`read_restart <read_restart>`
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commands.
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The :doc:`pair_modify <pair_modify>` command sets options for mixing of
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type I-J interaction coefficients and adding energy offsets or tail
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corrections to Lennard-Jones potentials. Details on these options as
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they pertain to individual potentials are described on the doc page
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for the potential. Likewise, info on whether the potential
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information is stored in a :doc:`restart file <write_restart>` is listed
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on the potential doc page.
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In the formulas listed for each pair style, *E* is the energy of a
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pairwise interaction between two atoms separated by a distance *r*\ .
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The force between the atoms is the negative derivative of this
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expression.
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If the pair_style command has a cutoff argument, it sets global
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cutoffs for all pairs of atom types. The distance(s) can be smaller
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or larger than the dimensions of the simulation box.
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Typically, the global cutoff value can be overridden for a specific
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pair of atom types by the :doc:`pair_coeff <pair_coeff>` command. The
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pair style settings (including global cutoffs) can be changed by a
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subsequent pair_style command using the same style. This will reset
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the cutoffs for all atom type pairs, including those previously set
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explicitly by a :doc:`pair_coeff <pair_coeff>` command. The exceptions
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to this are that pair_style *table* and *hybrid* settings cannot be
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reset. A new pair_style command for these styles will wipe out all
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previously specified pair_coeff values.
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----------
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Here is an alphabetic list of pair styles defined in LAMMPS. They are
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also given in more compact form in the pair section of :ref:`this page <cmd_5>`.
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Click on the style to display the formula it computes, arguments
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specified in the pair_style command, and coefficients specified by the
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associated :doc:`pair_coeff <pair_coeff>` command.
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There are also additional pair styles (not listed here) submitted by
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users which are included in the LAMMPS distribution. The list of
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these with links to the individual styles are given in the pair
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section of :ref:`this page <cmd_5>`.
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There are also additional accelerated pair styles (not listed here)
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included in the LAMMPS distribution for faster performance on CPUs and
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GPUs. The list of these with links to the individual styles are given
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in the pair section of :ref:`this page <cmd_5>`.
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* :doc:`pair_style none <pair_none>` - turn off pairwise interactions
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* :doc:`pair_style hybrid <pair_hybrid>` - multiple styles of pairwise interactions
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* :doc:`pair_style hybrid/overlay <pair_hybrid>` - multiple styles of superposed pairwise interactions
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* :doc:`pair_style zero <pair_zero>` - neighbor list but no interactions
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* :doc:`pair_style adp <pair_adp>` - angular dependent potential (ADP) of Mishin
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* :doc:`pair_style airebo <pair_airebo>` - AIREBO potential of Stuart
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* :doc:`pair_style airebo/morse <pair_airebo>` - AIREBO with Morse instead of LJ
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* :doc:`pair_style beck <pair_beck>` - Beck potential
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* :doc:`pair_style body <pair_body>` - interactions between body particles
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* :doc:`pair_style bop <pair_bop>` - BOP potential of Pettifor
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* :doc:`pair_style born <pair_born>` - Born-Mayer-Huggins potential
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* :doc:`pair_style born/coul/long <pair_born>` - Born-Mayer-Huggins with long-range Coulombics
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* :doc:`pair_style born/coul/long/cs <pair_born>` - Born-Mayer-Huggins with long-range Coulombics and core/shell
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* :doc:`pair_style born/coul/msm <pair_born>` - Born-Mayer-Huggins with long-range MSM Coulombics
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* :doc:`pair_style born/coul/wolf <pair_born>` - Born-Mayer-Huggins with Coulombics via Wolf potential
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* :doc:`pair_style brownian <pair_brownian>` - Brownian potential for Fast Lubrication Dynamics
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* :doc:`pair_style brownian/poly <pair_brownian>` - Brownian potential for Fast Lubrication Dynamics with polydispersity
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* :doc:`pair_style buck <pair_buck>` - Buckingham potential
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* :doc:`pair_style buck/coul/cut <pair_buck>` - Buckingham with cutoff Coulomb
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* :doc:`pair_style buck/coul/long <pair_buck>` - Buckingham with long-range Coulombics
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* :doc:`pair_style buck/coul/long/cs <pair_buck>` - Buckingham with long-range Coulombics and core/shell
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* :doc:`pair_style buck/coul/msm <pair_buck>` - Buckingham long-range MSM Coulombics
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* :doc:`pair_style buck/long/coul/long <pair_buck_long>` - long-range Buckingham with long-range Coulombics
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* :doc:`pair_style colloid <pair_colloid>` - integrated colloidal potential
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* :doc:`pair_style comb <pair_comb>` - charge-optimized many-body (COMB) potential
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* :doc:`pair_style comb3 <pair_comb>` - charge-optimized many-body (COMB3) potential
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* :doc:`pair_style coul/cut <pair_coul>` - cutoff Coulombic potential
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* :doc:`pair_style coul/debye <pair_coul>` - cutoff Coulombic potential with Debye screening
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* :doc:`pair_style coul/dsf <pair_coul>` - Coulombics via damped shifted forces
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* :doc:`pair_style coul/long <pair_coul>` - long-range Coulombic potential
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* :doc:`pair_style coul/long/cs <pair_coul>` - long-range Coulombic potential and core/shell
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* :doc:`pair_style coul/msm <pair_coul>` - long-range MSM Coulombics
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* :doc:`pair_style coul/streitz <pair_coul>` - Coulombics via Streitz/Mintmire Slater orbitals
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* :doc:`pair_style coul/wolf <pair_coul>` - Coulombics via Wolf potential
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* :doc:`pair_style dpd <pair_dpd>` - dissipative particle dynamics (DPD)
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* :doc:`pair_style dpd/tstat <pair_dpd>` - DPD thermostatting
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* :doc:`pair_style dsmc <pair_dsmc>` - Direct Simulation Monte Carlo (DSMC)
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* :doc:`pair_style eam <pair_eam>` - embedded atom method (EAM)
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* :doc:`pair_style eam/alloy <pair_eam>` - alloy EAM
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* :doc:`pair_style eam/fs <pair_eam>` - Finnis-Sinclair EAM
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* :doc:`pair_style eim <pair_eim>` - embedded ion method (EIM)
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* :doc:`pair_style gauss <pair_gauss>` - Gaussian potential
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* :doc:`pair_style gayberne <pair_gayberne>` - Gay-Berne ellipsoidal potential
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* :doc:`pair_style gran/hertz/history <pair_gran>` - granular potential with Hertzian interactions
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* :doc:`pair_style gran/hooke <pair_gran>` - granular potential with history effects
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* :doc:`pair_style gran/hooke/history <pair_gran>` - granular potential without history effects
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* :doc:`pair_style hbond/dreiding/lj <pair_hbond_dreiding>` - DREIDING hydrogen bonding LJ potential
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* :doc:`pair_style hbond/dreiding/morse <pair_hbond_dreiding>` - DREIDING hydrogen bonding Morse potential
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* :doc:`pair_style kim <pair_kim>` - interface to potentials provided by KIM project
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* :doc:`pair_style lcbop <pair_lcbop>` - long-range bond-order potential (LCBOP)
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* :doc:`pair_style line/lj <pair_line_lj>` - LJ potential between line segments
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* :doc:`pair_style lj/charmm/coul/charmm <pair_charmm>` - CHARMM potential with cutoff Coulomb
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* :doc:`pair_style lj/charmm/coul/charmm/implicit <pair_charmm>` - CHARMM for implicit solvent
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* :doc:`pair_style lj/charmm/coul/long <pair_charmm>` - CHARMM with long-range Coulomb
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* :doc:`pair_style lj/charmm/coul/msm <pair_charmm>` - CHARMM with long-range MSM Coulombics
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* :doc:`pair_style lj/class2 <pair_class2>` - COMPASS (class 2) force field with no Coulomb
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* :doc:`pair_style lj/class2/coul/cut <pair_class2>` - COMPASS with cutoff Coulomb
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* :doc:`pair_style lj/class2/coul/long <pair_class2>` - COMPASS with long-range Coulomb
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* :doc:`pair_style lj/cubic <pair_lj_cubic>` - LJ with cubic after inflection point
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* :doc:`pair_style lj/cut <pair_lj>` - cutoff Lennard-Jones potential with no Coulomb
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* :doc:`pair_style lj/cut/coul/cut <pair_lj>` - LJ with cutoff Coulomb
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* :doc:`pair_style lj/cut/coul/debye <pair_lj>` - LJ with Debye screening added to Coulomb
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* :doc:`pair_style lj/cut/coul/dsf <pair_lj>` - LJ with Coulombics via damped shifted forces
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* :doc:`pair_style lj/cut/coul/long <pair_lj>` - LJ with long-range Coulombics
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* :doc:`pair_style lj/cut/coul/long/cs <pair_lj>` - LJ with long-range Coulombics and core/shell
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* :doc:`pair_style lj/cut/coul/msm <pair_lj>` - LJ with long-range MSM Coulombics
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* :doc:`pair_style lj/cut/dipole/cut <pair_dipole>` - point dipoles with cutoff
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* :doc:`pair_style lj/cut/dipole/long <pair_dipole>` - point dipoles with long-range Ewald
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* :doc:`pair_style lj/cut/tip4p/cut <pair_lj>` - LJ with cutoff Coulomb for TIP4P water
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* :doc:`pair_style lj/cut/tip4p/long <pair_lj>` - LJ with long-range Coulomb for TIP4P water
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* :doc:`pair_style lj/expand <pair_lj_expand>` - Lennard-Jones for variable size particles
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* :doc:`pair_style lj/gromacs <pair_gromacs>` - GROMACS-style Lennard-Jones potential
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* :doc:`pair_style lj/gromacs/coul/gromacs <pair_gromacs>` - GROMACS-style LJ and Coulombic potential
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* :doc:`pair_style lj/long/coul/long <pair_lj_long>` - long-range LJ and long-range Coulombics
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* :doc:`pair_style lj/long/dipole/long <pair_dipole>` - long-range LJ and long-range point dipoles
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* :doc:`pair_style lj/long/tip4p/long <pair_lj_long>` - long-range LJ and long-range Coulomb for TIP4P water
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* :doc:`pair_style lj/smooth <pair_lj_smooth>` - smoothed Lennard-Jones potential
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* :doc:`pair_style lj/smooth/linear <pair_lj_smooth_linear>` - linear smoothed Lennard-Jones potential
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* :doc:`pair_style lj96/cut <pair_lj96>` - Lennard-Jones 9/6 potential
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* :doc:`pair_style lubricate <pair_lubricate>` - hydrodynamic lubrication forces
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* :doc:`pair_style lubricate/poly <pair_lubricate>` - hydrodynamic lubrication forces with polydispersity
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* :doc:`pair_style lubricateU <pair_lubricateU>` - hydrodynamic lubrication forces for Fast Lubrication Dynamics
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* :doc:`pair_style lubricateU/poly <pair_lubricateU>` - hydrodynamic lubrication forces for Fast Lubrication with polydispersity
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* :doc:`pair_style meam <pair_meam>` - modified embedded atom method (MEAM)
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* :doc:`pair_style mie/cut <pair_mie>` - Mie potential
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* :doc:`pair_style morse <pair_morse>` - Morse potential
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* :doc:`pair_style nb3b/harmonic <pair_nb3b_harmonic>` - nonbonded 3-body harmonic potential
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* :doc:`pair_style nm/cut <pair_nm>` - N-M potential
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* :doc:`pair_style nm/cut/coul/cut <pair_nm>` - N-M potential with cutoff Coulomb
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* :doc:`pair_style nm/cut/coul/long <pair_nm>` - N-M potential with long-range Coulombics
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* :doc:`pair_style peri/eps <pair_peri>` - peridynamic EPS potential
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* :doc:`pair_style peri/lps <pair_peri>` - peridynamic LPS potential
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* :doc:`pair_style peri/pmb <pair_peri>` - peridynamic PMB potential
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* :doc:`pair_style peri/ves <pair_peri>` - peridynamic VES potential
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* :doc:`pair_style polymorphic <pair_polymorphic>` - polymorphic 3-body potential
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* :doc:`pair_style reax <pair_reax>` - ReaxFF potential
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* :doc:`pair_style rebo <pair_airebo>` - 2nd generation REBO potential of Brenner
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* :doc:`pair_style resquared <pair_resquared>` - Everaers RE-Squared ellipsoidal potential
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* :doc:`pair_style snap <pair_snap>` - SNAP quantum-accurate potential
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* :doc:`pair_style soft <pair_soft>` - Soft (cosine) potential
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* :doc:`pair_style sw <pair_sw>` - Stillinger-Weber 3-body potential
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* :doc:`pair_style table <pair_table>` - tabulated pair potential
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* :doc:`pair_style tersoff <pair_tersoff>` - Tersoff 3-body potential
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* :doc:`pair_style tersoff/mod <pair_tersoff_mod>` - modified Tersoff 3-body potential
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* :doc:`pair_style tersoff/zbl <pair_tersoff_zbl>` - Tersoff/ZBL 3-body potential
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* :doc:`pair_style tip4p/cut <pair_coul>` - Coulomb for TIP4P water w/out LJ
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* :doc:`pair_style tip4p/long <pair_coul>` - long-range Coulombics for TIP4P water w/out LJ
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* :doc:`pair_style tri/lj <pair_tri_lj>` - LJ potential between triangles
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* :doc:`pair_style vashishta <pair_vashishta>` - Vashishta 2-body and 3-body potential
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* :doc:`pair_style yukawa <pair_yukawa>` - Yukawa potential
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* :doc:`pair_style yukawa/colloid <pair_yukawa_colloid>` - screened Yukawa potential for finite-size particles
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* :doc:`pair_style zbl <pair_zbl>` - Ziegler-Biersack-Littmark potential
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----------
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Restrictions
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""""""""""""
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This command must be used before any coefficients are set by the
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:doc:`pair_coeff <pair_coeff>`, :doc:`read_data <read_data>`, or
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:doc:`read_restart <read_restart>` commands.
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Some pair styles are part of specific packages. They are only enabled
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if LAMMPS was built with that package. See the :ref:`Making LAMMPS <start_3>` section for more info on packages.
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The doc pages for individual pair potentials tell if it is part of a
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package.
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Related commands
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""""""""""""""""
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:doc:`pair_coeff <pair_coeff>`, :doc:`read_data <read_data>`,
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:doc:`pair_modify <pair_modify>`, :doc:`kspace_style <kspace_style>`,
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:doc:`dielectric <dielectric>`, :doc:`pair_write <pair_write>`
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Default
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"""""""
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.. parsed-literal::
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pair_style none
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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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