Syntax:
create_box N region-ID
Examples:
create_box 2 mybox
Description:
This command creates a simulation box based on the specified region. Thus a region command must first be used to define a geometric domain.
The argument N is the number of atom types that will be used in the simulation.
If the region is not of style prism, then LAMMPS encloses the region (block, sphere, etc) with an axis-aligned (orthogonal) box which becomes the simulation domain.
If the region is of style prism, LAMMPS creates a non-orthogonal simulation domain shaped as a parallelepiped with triclinic symmetry. See the region prism command for a description of how the shape of the parallelepiped is defined. The parallelepiped has its "origin" at (xlo,ylo,zlo) and 3 edge vectors starting from its origin given by a = (xhi-xlo,0,0); b = (xy,yhi-ylo,0); c = (xz,yz,zhi-zlo).
A prism region used with the create_box command must have tilt factors (xy,xz,yz) that do not skew the box more than half the distance of the perpendicular box length. For example, if ylo = 2 and yhi = 12, then the y box length is 10 and the xy tilt factor must be between -5 and 5. Similarly, both xz and yz must be between -(zhi-zlo)/2 and +(zhi-zlo)/2. From a mechanics persepctive this is equivalent to saying the shear strain of the system (sideways displacement divided by perpendicular box length) must be between -0.5 and 0.5.
When a prism region is used, the simulation domain must be periodic in any dimensions with a non-zero tilt factor, as defined by the boundary command. I.e. if the xy tilt factor is non-zero, then both the x and y dimensions must be periodic. Similarly, x and z must be periodic if xz is non-zero and y and z must be periodic if yz is non-zero.
Restrictions:
An atom_style and region must have been previously defined to use this command.
Related commands:
Default: none