ortho = convert simulation box from non-orthogonal (triclinic) to orthogonal
  triclinic = convert simulation box from orthogonal to non-orthogonal (triclinic) 

Examples:

change_box ortho
change_box triclinic 

Description:

By default LAMMPS runs a simulation in an orthogonal, axis-aligned simulation box. LAMMPS can also run simulations in non-orthogonal (triclinic) simulation boxes. A box is defined as either orthogonal or non-orthogonal when it is created via the create_box, read_data, or read_restart commands.

This command allows you to toggle the existing simulation box from orthogonal to non-orthogonal and vice versa. For example, an initial equilibration simulation can be run in an orthogonal box, the box can be toggled to non-orthogonal, and then a non-equilibrium MD (NEMD) simulation can be run with deformation via the fix deform command.

Note that if the simulation box is currently non-orthogonal and has non-zero tilt in xy, yz, or xz, then it cannot be converted to an orthogonal box.

Restrictions:

At the point in the input script when this command is issued, no dumps can be active, nor can a fix ave/spatial or fix deform be active. This is because these commands test whether the simulation box is orthogonal when they are first issued. Note that these commands can appear in your script before a change_box command is issued, so long as an undump or unfix command is also used to turn them off.

Related commands: none

Default: none