mirror of https://github.com/lammps/lammps.git
65 lines
2.2 KiB
Plaintext
65 lines
2.2 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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fix wall/lj126 command :h3
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[Syntax:]
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fix ID group-ID wall/lj126 style coord epsilon sigma cutoff :pre
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ID, group-ID are documented in "fix"_fix.html command
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wall/lj126 = style name of this fix command
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style = {xlo} or {xhi} or {ylo} or {yhi} or {zlo} or {zhi}
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coord = position of wall
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epsilon = Lennard-Jones epsilon for wall-particle interaction
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sigma = Lennard-Jones sigma for wall-particle interaction
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cutoff = distance from wall at which wall-particle interaction is cut off :ul
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[Examples:]
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fix wallhi all wall/lj126 xhi 10.0 1.0 1.0 1.12 :pre
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[Description:]
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Bound the simulation domain with a Lennard-Jones wall that encloses
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the atoms. The energy E of a wall-particle interactions is given by
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the 12-6 potential
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:c,image(Eqs/pair_lj.jpg)
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where {r} is the distance from the particle to the wall {coord}, and
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epsilon and sigma are the usual LJ parameters. Rc is the cutoff value
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specified in the command. This interaction provides a harder, more
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repulsive interaction with the wall than the softer 9-3 potential
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provided by the "fix wall/lj93"_fix_wall_lj93.html command.
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The wall potential is shifted so that the energy of a wall-particle
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interaction is 0.0 at the cutoff distance.
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This fix supports the "fix_modify"_fix_modify.html options for
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{thermo} and {energy}. The former will print the contribution the fix
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makes to the energy of the system when thermodynamics is printed,
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where the energy of each particle comes from the integrated form of
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the equation above. The latter will add this contribution to the
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total potential energy (PotEng).
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The forces due to this fix are also imposed during an energy
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minimization, invoked by the "minimize"_minimize.html command. If you
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want that energy to be included in the total potential energy of the
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system (the quantity being minimized), you must enable the
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"fix_modify"_fix_modify.html {energy} option for this fix.
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[Restrictions:] none
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[Related commands:]
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"fix wall/reflect"_fix_wall_reflect.html, "fix
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wall/lj93"_fix_wall_lj93.html
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[Default:] none
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