forked from lijiext/lammps
119 lines
3.9 KiB
Plaintext
119 lines
3.9 KiB
Plaintext
"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 born/coul/long command :h3
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[Syntax:]
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pair_style born/coul/long cutoff (cutoff2) :pre
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cutoff = global cutoff for 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 born/coul/long 10.0
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pair_style born/coul/long 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 :pre
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[Description:]
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This pair style compute the Born-Mayer-Huggins potential described in
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"(Fumi and Tosi)"_#FumiTosi, given by
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:c,image(Eqs/pair_born.jpg)
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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 the last term represents
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the usual Coulombic pairwise interaction between atoms I and J. In
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the Coulombic term, k is an energy-conversion constant, Qi and Qj are
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the charges on the 2 atoms, and epsilon is the dielectric constant
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which can be set by the "dielectric"_dielectric.html command.
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If one cutoff is specified in the pair_style command, it is used for
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both the A,C,D and Coulombic terms. If two cutoffs are specified, the
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first is used as the cutoff for the A,C,D terms, and the second is the
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cutoff for the Coulombic term.
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Note that this potential is identical to the "Buckingham
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potential"_pair_buck.html when sigma = D = 0.
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An additional damping factor is applied to the Coulombic term so it
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can be used in conjunction with the "kspace_style"_kspace_style.html
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command and its {ewald} or {pppm} option. The Coulombic cutoff
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specified for this style means that pairwise interactions within this
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distance are computed directly; interactions outside that distance are
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computed in reciprocal space.
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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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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) :ul
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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. Only the A,C,D
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cutoff can be specified since a Coulombic cutoff cannot be specified
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for an individual I,J type pair. All type pairs use the same global
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Coulombic cutoff specified in the pair_style command.
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:line
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[Mixing, shift, table, tail correction, restart, rRESPA info]:
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This style does not support mixing. Thus, coefficients for all
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I,J pairs must be specified explicitly.
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This style supports the "pair_modify"_pair_modify.html 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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This style does not support the "pair_modify"_pair_modify.html
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table option since a tabulation capability has not yet been added to
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this potential.
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This style does not support the pair_modify tail option for
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adding long-range tail corrections to energy and pressure.
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This style writes its information to binary
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"restart"_restart.html files, so pair_style and pair_coeff commands do
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not need to be specified in an input script that reads a restart file.
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This style only supports the {pair} keyword of run_style respa.
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See the "run_style"_run_style.html command for details.
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:line
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[Restrictions:]
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The {born/coul/long} style is part of the "kspace" package. It is
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only enabled if LAMMPS was built with that package (which it is by
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default). See the "Making LAMMPS"_Section_start.html#2_3 section for
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more info.
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[Related commands:]
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"pair_coeff"_pair_coeff.html, "pair_style buck"_pair_buck.html
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[Default:] none
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:line
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:link(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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