forked from lijiext/lammps
138 lines
5.0 KiB
Plaintext
Executable File
138 lines
5.0 KiB
Plaintext
Executable File
"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 dipole/cut command :h3
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[Syntax:]
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pair_style dipole/cut cutoff (cutoff2) :pre
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cutoff = global cutoff LJ (and Coulombic if only 1 arg) (distance units)
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cutoff2 = global cutoff for Coulombic (optional) (distance units) :ul
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[Examples:]
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pair_style dipole/cut 10.0
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pair_coeff * * 1.0 1.0
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pair_coeff 2 3 1.0 1.0 2.5 4.0 :pre
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[Description:]
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Style {dipole/cut} computes interactions bewteen pairs of particles
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that each have a charge and/or a point dipole moment. In addition to
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the usual Lennard-Jones interaction between the particles (Elj) the
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charge-charge (Eqq), charge-dipole (Eqp), and dipole-dipole (Epp)
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interactions are computed by these formulas for the energy (E), force
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(F), and torque (T) between particles I and J.
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:c,image(Eqs/pair_dipole.jpg)
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where qi and qj are the charges on the two particles, pi and pj are
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the dipole moment vectors of the two particles, r is their separation
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distance, and the vector r = Ri - Rj is the separation vector between
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the two particles. Note that Eqq and Fqq are simply Coulombic energy
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and force, Fij = -Fji as symmetric forces, and Tij != -Tji since the
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torques do not act symmetrically. These formulas are discussed in
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"(Allen)"_#Allen and in "(Toukmaji)"_#Toukmaji.
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If one cutoff is specified in the pair_style command, it is used for
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both the LJ and Coulombic (q,p) terms. If two cutoffs are specified,
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they are used as cutoffs for the LJ and Coulombic (q,p) terms
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respectively.
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Use of this pair style requires the use of the "fix
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nve/dipole"_fix_nve_dipole.html command to integrate rotation of the
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dipole moments. Additionally, "atom_style dipole"_atom_style.html
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should be used since it defines the point dipoles and their rotational
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state. The magnitude of the dipole moment for each type of particle
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can be defined by the "dipole"_dipole.html command or in the "Dipoles"
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section of the data file read in by the "read_data"_read_data.html
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command. Their initial orientation can be defined by the "set
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dipole"_set.html command or in the "Atoms" section of the data file.
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The following coefficients must be defined for each pair of atoms
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types via the "pair_coeff"_pair_coeff.html 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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"read_data"_read_data.html or "read_restart"_read_restart.html
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commands, or by mixing as described below:
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epsilon (energy units)
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sigma (distance units)
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cutoff1 (distance units)
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cutoff2 (distance units) :ul
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The latter 2 coefficients are optional. If not specified, the global
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LJ and Coulombic cutoffs specified in the pair_style command are used.
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If only one cutoff is specified, it is used as the cutoff for both LJ
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and Coulombic interactions for this type pair. If both coefficients
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are specified, they are used as the LJ and Coulombic cutoffs for this
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type pair.
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:line
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[Mixing, shift, table, tail correction, per-atom energy/stress,
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restart, rRESPA info]:
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For atom type pairs I,J and I != J, the epsilon and sigma coefficients
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and cutoff distances for this pair style can be mixed. The default
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mix value is {geometric}. See the "pair_modify" command for details.
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For atom type pairs I,J and I != J, the A, sigma, d1, and d2
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coefficients and cutoff distance for this pair style can be mixed. A
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is an energy value mixed like a LJ epsilon. D1 and d2 are distance
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values and are mixed like sigma. The default mix value is
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{geometric}. See the "pair_modify" command for details.
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This pair style supports the "pair_modify"_pair_modify.html shift
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option for the energy of the Lennard-Jones portion of the pair
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interaction.
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The "pair_modify"_pair_modify.html table option is not relevant
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for this pair style.
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This pair style does not support the "pair_modify"_pair_modify.html
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tail option for adding long-range tail corrections to energy and
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pressure.
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This pair style can calculate per-atom energy and stress, as used by
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the "compute epair/atom"_compute_epair_atom.html, "compute
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stress/atom"_compute_stress_atom.html, and "dump custom"_dump.html
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commands.
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This pair style writes its information to "binary restart
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files"_restart.html, so pair_style and pair_coeff commands do not need
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to be specified in an input 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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"run_style respa"_run_style.html command. It does not support the
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{inner}, {middle}, {outer} keywords of the "run_style
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command"_run_style.html.
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[Restrictions:]
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This style is part of the "dipole" package. It is only enabled if
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LAMMPS was built with that package. See the "Making
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LAMMPS"_Section_start.html#2_3 section for more info.
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[Related commands:]
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"pair_coeff"_pair_coeff.html, "fix nve/dipole"_fix_nve_dipole.html,
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"compute temp/dipole"_compute_temp_dipole.html
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[Default:] none
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:line
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:link(Allen)
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[(Allen)] Allen and Tildesley, Computer Simulation of Liquids,
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Clarendon Press, Oxford, 1987.
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:link(Toukmaji)
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[(Toukmaji)] Toukmaji, Sagui, Board, and Darden, J Chem Phys, 113,
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10913 (2000).
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