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fix wall/lj126 command

Syntax:

fix ID group-ID wall/lj126 style coord epsilon sigma cutoff 

Examples:

fix wallhi all wall/lj126 xhi 10.0 1.0 1.0 1.12 

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 12-6 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 provides a harder, more repulsive interaction with the wall than the softer 9-3 potential provided by the fix wall/lj93 command.

The wall potential is shifted so that the energy of a wall-particle interaction is 0.0 at the cutoff distance.

Restart, fix_modify, output, run start/stop, minimize info:

No information about this fix is written to binary restart files.

The fix_modify energy option is supported by this fix to add the energy of interaction between atoms and the wall to the system's potential energy as part of thermodynamic output.

This fix computes a scalar energy and a 3-vector of forces (on the wall), which can be accessed by various output commands. The scalar and vector values calculated by this fix are "extensive", meaning they scale with the number of atoms in the simulation.

No parameter of this fix can be used with the start/stop keywords of the run command.

The forces due to this fix are imposed during an energy minimization, invoked by the minimize command.

IMPORTANT NOTE: If you want the atom/wall interaction 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:

Any dimension (xyz) that has a LJ 12/6 wall must be non-periodic.

Related commands:

fix wall/reflect, fix wall/lj93

Default: none