fix_modify AtC mesh create_faceset <id> box <xmin> <xmax> <ymin> <ymax> <zmin> <zmax> <in|out> [units]
fix_modify AtC mesh create_faceset obndy box -4.0 4.0 -12 12 -12 12 out
Command to assign an id to a set of FE faces.
Only viable for rectangular grids.
The default options are units = lattice and the use of outer faces