PBC in databases when cell is undefined
This MR proposes a tiny change in the way the Atoms' periodic boundary conditions (PBC) are processed/stored in the ASE databases.
In the current master, when writing an Atoms object with an undefined cell
to a database, the PBC stored in the database is automatically set to
[False, False, False], regardless of the Atoms'
I don't know if there was a particular reason to have it that
way, but I think it makes more sense to simply always use the
attribute of the Atoms object in question.
(This has roots in my ongoing work of unifying the standard and
variable-cell functionality in
ase.ga, where I would like databases
to be able to contain template structures like