# Extended Hückel method: what are the atomic orbital energies usually used?

I was checking out an extended Hückel (non-iterative) code, and realised that for s-block elements it would be impossible to simply use atomic ionisation energies as an approximation to the orbital potential energies (due to the p orbitals being empty). In this case, what values are used?

It has $$H_{vv}$$ terms for different orbitals of all elements of the table.