N-electron wavefunction quality

[mzmansour]

Is there is a way to check the quality of N-electron orbitals?
How I know that I do not need more orbitals to be included in calculations?

[mzmansour]

I think it depends on the accuracy you want.

You can compare the calculated energy levels with the experimental ones ( or NIST tables)
and/or compare the calculated transition probabilities with the experiments ( or NIST tables)