Syntax:
fix ID group-ID wall/lj93 style coord epsilon sigma cutoff
Examples:
fix wallhi all wall/lj93 xhi 10.0 1.0 1.0 2.5
Description:
Bound the simulation domain with a Lennard-Jones wall that encloses the atoms. The energy E of a wall-particle interactions is given by the 9-3 potential
where r is the distance from the particle to the wall coord, and epsilon and sigma are the usual LJ parameters. Rc is the cutoff value specified in the command. This interaction is derived by integrating over a 3d half-lattice of Lennard-Jones 12-6 particles. A harder, more repulsive wall interaction can be computed by using the fix wall/lj126 command.
The wall potential is shifted so that the energy of a wall-particle interaction is 0.0 at the cutoff distance.
This fix makes a contribution to the potential energy of the system that can be included in thermodynamic output of potential energy using the fix_modify energy option. The contribution can also be printed by itself via the keyword f_fix-ID in the thermo_style custom command.
The forces due to this fix are also imposed during an energy minimization, invoked by the minimize command. If you want that energy to be included in the total potential energy of the system (the quantity being minimized), you must enable the fix_modify energy option for this fix.
Restrictions: none
Related commands:
fix wall/reflect, fix wall/lj126
Default: none