Regarding the example lattic for rocksalt structure

Alloy Theoretic Automated Toolkit (ATAT)
1

The example files include the rocksalt lattice structure shown as below:

1 1 1 90 90 90
0 0.5 0.5
0.5 0 0.5
0.5 0.5 0
0 0 0 A,B
0.5 0.5 0.5 O
which gives only half the number of atoms when generated using the mcsqs and another question is the real rocksalt structure say for example NaCl has a completely different structure as given below:
3.798 3.798 3.798 90 90 90
1 0 0
0 1 0
0 0 1
0.0000000000000000 0.0000000000000000 0.0000000000000000 A,B
0.0000000000000000 0.5000000000000000 0.5000000000000000 A,B
0.5000000000000000 0.0000000000000000 0.5000000000000000 A,B
0.5000000000000000 0.5000000000000000 0.0000000000000000 A,B
0.0000000000000000 0.0000000000000000 0.5000000000000000 O
0.0000000000000000 0.5000000000000000 0.0000000000000000 O
0.5000000000000000 0.0000000000000000 0.0000000000000000 O
0.5000000000000000 0.5000000000000000 0.5000000000000000 O
This structure makes far more sense and is easy to understand for the users and when visualized using any visualization software reveals the true rocksalt structure with correct no. of atomic positions which is missing in the structure present in your given example directory.

Therefore, it is my request to you kindly look into it and if possible try to answer my queries as soon as possible.

Regards
Marif Manzoor

2

Dear Marif Manzoor,

Sorry about the late reply! Maybe you already figured it out, but I will leave a reply in case someone else comes searching. The example files contain the primitive rocksalt lattice, while the lattice you supply is the conventional cell. They are in principle equivalent (and you can absolutely choose to use the conventional cell in your calculations) but there are some benefits to using the smaller primitive cell. Specifically, it is more flexible in terms of size, shape, and concentrations, the symmetry calculations are faster and less likely to fail, as well as simplifying defining paths for electronic structure or phonon calculations in reciprocal space. Additionally, the example cell has lattice constant equal to 1 in order to define cutoffs in units of lattice constants.

If you want your generated cells to have a specific shape commensurate with the conventional cell, you can use mcsqs -rc and supply a sqscell.out, for instance using

1

2 0 0

0 2 0

0 0 2

will give you a 2x2x2 64 atom conventional cell.

Best regards,

Solveig Aamlid