2006-09-22 00:22:34 +08:00
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"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
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:link(lws,http://lammps.sandia.gov)
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:link(ld,Manual.html)
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:link(lc,Section_commands.html#comm)
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:line
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pair_style command :h3
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[Syntax:]
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pair_style style args :pre
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style = one of the following :ulb,l
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2007-02-10 05:37:30 +08:00
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{none}, {hybrid}, {buck}, {buck/coul/cut}, {buck/coul/long}, {dpd},
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{eam}, {eam/alloy} or {eam/fs}, {gran/hertzian}, {gran/history},
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{gran/no_history}, {lj/charmm/coul/charmm},
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{lj/charmm/coul/charmm/implicit} or {lj/charmm/coul/long},
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{lj/class2}, {lj/class2/coul/cut} or {lj/class2/coul/long}, {lj/cut},
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{lj/cut/coul/cut} or {lj/cut/coul/debye}, {lj/cut/coul/long},
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{lj/cut/coul/long/tip4p}, {lj/expand}, {lj/smooth}, {meam}, {morse},
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{soft}, {sw}, {table}, {tersoff}, {yukawa} :ul
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2006-09-22 00:22:34 +08:00
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args = arguments used by a particular style :l,ule
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[Examples:]
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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 :pre
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[Description:]
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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 "bond_style"_bond_style.html 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 classed as "pairwise"
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2006-11-29 01:00:29 +08:00
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potential because the set of interacting atoms changes with time
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(unlike a bonded system) and thus a neighbor list is used to find
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nearby interacting atoms.
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2006-09-22 00:22:34 +08:00
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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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"pair_coeff"_pair_coeff.html command or read from a file by the
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"read_data"_read_data.html or "read_restart"_read_restart.html
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commands. Mixing, shifting, and tail corrections for the potentials
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is discussed is the documentation for the
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"pair_modify"_pair_modify.html command.
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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 "pair_coeff"_pair_coeff.html 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 "pair_coeff"_pair_coeff.html 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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:line
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Here is an alphabetic list of pair styles defined in LAMMPS. Click on
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the style to display the formula it computes, arguments specified in
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the pair_style command, and coefficients specified by the associated
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"pair_coeff"_pair_coeff.html command:
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2007-02-10 05:37:30 +08:00
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"pair_style none"_pair_none.html - turn off pairwise interactions
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"pair_style hybrid"_pair_hybrid.html - define multiple styles of pairwise interactions :ul
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"pair_style buck"_pair_buck.html - Buckingham potential
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"pair_style buck/coul/cut"_pair_buck.html - Buckinhham with cutoff Coulomb
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"pair_style buck/coul/long"_pair_buck.html - Buckingham with long-range Coulomb
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"pair_style dpd"_pair_dpd.html - dissipative particle dynamics (DPD)
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"pair_style eam"_pair_eam.html - embedded atom method (EAM)
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"pair_style eam/alloy"_pair_eam.html - alloy EAM
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"pair_style eam/fs"_pair_eam.html - Finnis-Sinclair EAM
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2007-04-20 07:25:27 +08:00
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"pair_style gayberne"_pair_gayberne.html - Gay-Berne ellipsoidal potential
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2007-04-07 02:31:02 +08:00
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"pair_style gran/hertzian"_pair_gran.html - granular potential with Hertizain interactions
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"pair_style gran/history"_pair_gran.html - granular potential with history effects
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"pair_style gran/no_history"_pair_gran.html - granular potential without history effects
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2007-02-10 05:37:30 +08:00
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"pair_style lj/charmm/coul/charmm"_pair_charmm.html - CHARMM potential with cutoff Coulomb
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"pair_style lj/charmm/coul/charmm/implicit"_pair_charmm.html - CHARMM for implicit solvent
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"pair_style lj/charmm/coul/long"_pair_charmm.html - CHARMM with long-range Coulomb
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"pair_style lj/class2"_pair_class2.html - COMPASS (class 2) force field with no Coulomb
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"pair_style lj/class2/coul/cut"_pair_class2.html - COMPASS with cutoff Coulomb
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"pair_style lj/class2/coul/long"_pair_class2.html - COMPASS with long-range Coulomb
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"pair_style lj/cut"_pair_lj.html - cutoff Lennard-Jones potential with no Coulomb
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"pair_style lj/cut/coul/cut"_pair_lj.html - LJ with cutoff Coulomb
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"pair_style lj/cut/coul/debye"_pair_lj.html - LJ with Debye damping added to Coulomb
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"pair_style lj/cut/coul/long"_pair_lj.html - LJ with long-range Coulomb
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"pair_style lj/cut/coul/long/tip4p"_pair_lj.html - LJ with long-range Coulomb for TIP4P water
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"pair_style lj/expand"_pair_lj_expand.html - Lennard-Jones for variable size particles
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"pair_style lj/smooth"_pair_lj_smooth.html - smoothed Lennard-Jones potential
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"pair_style meam"_pair_meam.html - modified embedded atom method (MEAM)
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"pair_style morse"_pair_morse.html - Morse potential
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"pair_style soft"_pair_soft.html - Soft (cosine) potential
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"pair_style sw"_pair_sw.html - Stillinger-Weber 3-body potential
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"pair_style table"_pair_table.html - tabulated pair potential
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"pair_style tersoff"_pair_tersoff.html - Tersoff 3-body potential
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"pair_style yukawa"_pair_yukawa.html - Yukawa potential :ul
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2006-09-22 00:22:34 +08:00
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:line
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[Restrictions:]
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This command must be used before any coefficients are set by the
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"pair_coeff"_pair_coeff.html, "read_data"_read_data.html, or
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"read_restart"_read_restart.html 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 "Making
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LAMMPS"_Section_start.html#2_2 section for more info.
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[Related commands:]
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"pair_coeff"_pair_coeff.html, "read_data"_read_data.html,
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"pair_modify"_pair_modify.html, "kspace_style"_kspace_style.html,
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"dielectric"_dielectric.html, "pair_write"_pair_write.html
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[Default:]
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pair_style none :pre
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