What unit of energy does PySCF use?

The documentation for PySCF can be found here: https://sunqm.github.io/pyscf/

However, it does not explicitly state in the documentation what unit of energy is used. Is there a way to find this out?

Same as any other electronic structure code: atomic units are used. The unit of energy is Hartree, $$E_h$$, in which the ground state energy of hydrogen is exactly $$-0.5$$. One Hartree is roughly 27.211 386 245 988 eV, see the NIST database. The atomic unit for length is the Bohr radius, $$a_0$$.