Occupancy rules
Conventional volume
-
Press Cell->Remove and press over the cell to remove it.
Press Cell->Create and set System to c, Lattice
to P and the lattice parameter a to 1.
In the Type page, set the number of conventional cells
to 5, 5, 5, and press Ok to create
the cell. Press Save and then Ok, to save the empty
cell.
- Repeat the Cell->Link task, linking the cell volume
with the Si atom, with the pattern (*2_, *, *).
The left side of the cell is occupied with Si atoms. Repeat the
Cell->Link task, this time linking with a C atom, with
the pattern (_2*, *, *). The right side
of the cell is occupied with C atoms.
- Press Save and move Backward once, to recover the
empty cell, then press Ok.
To create 8 alternating octant cubes, four with Si and four with
C atoms, repeat the Cell->Link task 4 times with a Si atom,
with the rules
(*2_, *2_, *2_), (_2*, _2*, *2_),
(_2*, *2_, _2*), (*2_, _2*, _2*)
and another 4 times with a C atom, with the rules
(*2_, *2_, _2*), (_2*, _2*, _2*),
(_2*, *2_, *2_), (*2_, _2*, *2_).
- Press Save and move Backward once, to recover the
empty cell, then press Ok.
Repeat the Cell->Link task, linking the cell volume
with the Si atom, with the pattern (*_, *_, *_).
Alternating nodes, half of the total, are now occupied with Si atoms.
Repeat the Cell->Link task, this time linking with a C atom,
with the pattern (_*, _*, _*). The other half
of the alternating nodes is now occupied with C atoms.
- Press Save and move Backward once, to recover the
empty cell, then press Ok.
Press Cell->Modify and change, in the Type page,
the number of cells to 6, 6, 6, in the
Origin page, the Axes to Yes, and press Ok.
The first (red), second (green) third (blue) axes are now
visible at the corner of the increased cell volume.
Press Cell->Modify again and change, in the Origin
page, the origin node coordinates to 3, 3, 3,
then press Ok. The node origin is now at the center of the
cell volume, although the physical origin remains the same.
- Repeat the Cell->Link task, linking the cell volume with
the Si atom, with the pattern (*1, *1, *1).
A cube with 3x3x3 nodes in the center of the cell is now occupied
with Si atoms.
Repeat the Cell->Link task, this time linking with a C atom,
with the pattern (__****, __****, __****). All nodes
around the 3x3x3 central nodes are now occupied with C atoms.