This is a tool for building models in CAC. Commands and usage options are below.
## Flow of commands
```flow
op1=>operation: Define atom types and lattices to be used
op2=>operation: Define regions and build
op3=>operation: Define modifiers
op4=>operation: Output data files
op1->op2->op3->op4
```
## Command syntax
### Atom types command
```
atom_types num_atoms {name mass}
```
The parameters for the atoms command are:
`num_atoms` - number of atom types defined for this model building session
`{}` - indicate that the contents must be repeated `num_atoms` times.
`name` - Elemental name of atom
`mass` - mass of the atom
This command should only be called once, defining all atoms in one go. The atom types will then be defined in numeric order with the first atom defined being type one and the last one being type `num_atoms`.
`lattice_type` - One of predefined lattice types which specifies the element type used. Current accepted options are: `FCC`
`type` - Optional keyword which defines the atom type used for the lattice. This is used in place of basis if atoms are at lattice positions in these elements.
`atom_type` - The atom type which corresponds to the atoms at the lattice positions of the current element
`basis` - Optional keyword which is used in order to define the basis atoms instead of using the default definition. If basis is not included the following commands also are not included.
`num_basis_atoms` are the number of basis atoms in this element.
`{}` - indicate that the contents must be repeated `num_basis_atoms` times.
`type` - the atom type of the atom.
`posx posy posz` - The position of the basis atom relative to the lattice point at (0,0,0)
**Either type or basis keywords must be present in the lattice command, both cannot be used.**
## Region Command
```
region id lattice_id element_size units lenx leny lenz [zigzag] [origin x y z] [cat region_id dim [nomatch]] [orient [hkl] [hkl] [hkl]]
```
`id` - User defined id for this region
`lattice_id` - The lattice type for this region
`element_size` - The element size used for this region defined as the number of atoms per element edge. An element size of 2 means that this region is at full atomistic resolution.
`units` - Either `lattice` or `box` which adjusts how the length values are calculated. Units `lattice` means the region will consist of `len` number of elements for every dim. Units `box` are defined in angstroms.
`lenx leny lenz` - The lengths of the box in each dimension in the user defined units
`zigzag` - Optional keyword which specifies if regions built with elements should have filled in boundaries (using atoms). If zigzag isn't present then the regions are built with filled in boundaries by default
`origin x y z` - Optional keyword which specifies the origin of the current region in angstroms. The region boundaries are then (x, x+lenx), (y, y+leny), (z,z+lenz).
`cat region_id outregionid dim [nomatch] ` - Optional keyword which stacks the current region on the face of another region defined by `dim`. `region_id` is the id of the region which is already build. `outregionid` is the user defined id of the combined stacked region which can be used with further merge commands. Default behavior is to expand the smallest region to match the larger one, using the optional keyword `nomatch` preserves the original regions and does not attempt to match the boundaries.
`orient [hkl] [hkl] [hkl]` simply orients the unit cell of this region. This defaults to [100] [010] [001]
