Store self.atoms in VASP calculator

The Vasp calculator does currently only store None to self.atoms when the calculator is instanciated. Usually, you would then call calc.initialize(atoms) to initialize things, e.g. self.atoms_sorted.

However, there are still functions in the Vasp calculator which asks for self.atoms, so I was thinking that calc.initialize(atoms) should store the atoms object as well. This is where I'm not sure which behavior we would expect: Should self.atoms store the sorted or the unsorted atoms object?

For instance, the calc.get_atoms() function doesn't work either, as it tries to copy a None object (unless you do a restart, in which case the atoms are stored in self.atoms somewhere).