How does CubicSupercellTransformation work?

[adosar]

Hello, I have looked at the source code but I can't understand how CubicSupercellTransformation from the pymatgen.transformations_advanced_transformations module work. Can someone explain how we arrive at a cubic supercell starting from a non-cubic unit cell?

[mkhorton]

It’s a supercell of the input cell. For any input, it’s always possible to define a supercell with ~approximately orthogonal vectors, it’s just a question of how big the supercell is, and how approximate is acceptable.

It can be useful in a variety of contexts for different modelling software, e.g. some TEM image simulation codes.

What’s important to understand is that even if you have it in this cubic-like setting, the symmetry and primitive cell of the crystal have not changed.

[adosar]

I have added a picture representing a unit cell (2D for ease of visualization) and a 3x3 supercell. How this supercell can be made cubic?