Understanding orbital values

Dear all,

I am trying to understand the meaning of the output files when running something like

set_options({"cubeprop_tasks": ["orbitals"]})
E, wfn = energy("hf", return_wfn=True)
cubeprop(wfn)

As specified in the documentation, I get one file for each orbital. Those files typically contain real-valued numbers, both < 0 and > 0. As the wavefunction would in general be complex-valued, and densities positive real-valued, I am confused as to what specifically those numbers represent. The header of the cube-files specifies something like

Isocontour range for 85% of the density: (0.0456266,-0.0459855)

which makes it seem like an electron density. Contrary to cube-files generated using psi4.set_options({"cubeprop_tasks": ["density"]}), there is no unit such as [e/a0^3] specified.

Thank you for any help and best regards,
Clemens

Only real-valued orbitals are considered. It is a typical constraints to help with implementation and theory.
Complex-valued theories are much less developed.

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