Can we begin at the beginning When chemists put a standard electron configuration for an element what do those numbers represent Do they mean to suggest that each of those pairs of electrons occupies a mere Slatter determinant  That they sit in things that are no more real than a basis function like the cartesian axes are basis functions for vectors And any old set of basis functions could be used instead Or do these electrons reside in pairs in HartreeFock orbitals which now justso happen to be called d somethingorother as though they WERE a hydrogenic atomic orbitals even though they arent What DO those numbers mean in an atoms electron configuration notation Do they now mean the first two quantumnumbers of the oneelectron HartreeFock wavefuctions and were now highjacked Schroediger hydrogenic notation for them but forgot to tell anybody Inquiring minds want to know