I tried to circumvent this one...
... as in my understanding QM / QED simply is the propper way to describe interaction of charges in the "experiment atom", we'd else "stand-alone" would consider to be bound to objects like nucleii and electrons .
(that's why i did put "occupied" in quotation marks, for example)
With QM, the classical point-type charges have to be replaced with the respective Hammiltonians, and the respective "interaction" has to be analyzed... but that's all of the difference there is, in my opinion
so, I felt kind of justified to do so.
However, the math resulting thereof is quite more complex than with classical point charges, agreed, and the results more often than not are counter-intuitive, even contradicting classical approaches.
But , in the light of this theory, I never did get the meaning of for example the "spin" you mentioned right anyway, with electrons not even being "there" belonging to...
...so maybe QM really is inexplicable in a psychologically pleasing, non mind-boggling way, from a certain point on, and better should be left to it's own devices, i.e. mathematical expressions
just my 2 cents..