Default behavior when creating supercell

[shipinqin]

Supercells created with pymatgen seems to always fold sites into the unit cell, which may not be ideal as folding sites back into unit cell is fairly simple, but unfolding them may not be so straightforward at times. Is there any plan to change this default behavior in future versions?

I found two simple ways (maybe there is more?) to create supercells in pymatgen:

1. Multiply the structure with a matrix directly, which calls the pymatgen.core.IStructure.__mul__ function. It always returns a Structure with to_unit_cell=True.
2. Use pymatgen.core.Structure.make_supercell. This function comes with an option to change to_unit_cell. However, since the supercell in this function is created by calling the __mul__ function above, setting to_unit_cell=False will not behave as expected.

[DanielYang59]

Hi @shipinqin thanks for reporting. I believe both should work but looks like there's a bug (to fold sites into the cell when to_unit_cell=False), I could recreate this and would fix this #4571