forked from lijiext/lammps
80 lines
2.5 KiB
Plaintext
80 lines
2.5 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/lj93 command :h3
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[Syntax:]
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fix ID group-ID wall/lj93 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/lj93 = 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/lj93 xhi 10.0 1.0 1.0 2.5 :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 9-3 potential
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:c,image(Eqs/fix_wall_lj93.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 is derived by integrating
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over a 3d half-lattice of Lennard-Jones 12-6 particles. A harder,
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more repulsive wall interaction can be computed by using the "fix
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wall/lj126"_fix_wall_lj126.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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[Restart, fix_modify, output, run start/stop, minimize info:]
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No information about this fix is written to "binary restart
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files"_restart.html.
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The "fix_modify"_fix_modify.html {energy} option is supported by this
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fix to add the energy of interaction between atoms and the wall to the
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system's potential energy as part of "thermodynamic
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output"_thermo_style.html.
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This fix computes a scalar energy and a 3-vector of forces (on the
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wall), which can be accessed by various "output
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commands"_Section_howto.html#4_15.
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No parameter of this fix can be used with the {start/stop} keywords of
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the "run"_run.html command.
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The forces due to this fix are imposed during an energy minimization,
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invoked by the "minimize"_minimize.html command.
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IMPORTANT NOTE: If you want the atom/wall interaction energy to be
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included in the total potential energy of the system (the quantity
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being minimized), you MUST enable the "fix_modify"_fix_modify.html
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{energy} option for this fix.
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[Restrictions:]
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Any dimension (xyz) that has a LJ 9/3 wall must be non-periodic.
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[Related commands:]
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"fix wall/reflect"_fix_wall_reflect.html, "fix
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wall/lj126"_fix_wall_lj126.html
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[Default:] none
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