Doing the following in Python:
hf_energy = psi4.energy(‘hf/sto-6g’, molecule=mol, return_wfn=False)
psi4.set_options({‘num_frozen_docc’ : ‘2’, ‘num_frozen_uocc’ : ‘4’, ‘active’ : ‘4’})
cc_energy = psi4.energy(‘ccsd/sto-6g’, molecule=mol, return_wfn=False)
ci_energy = psi4.energy(‘fci/sto-6g’, molecule=mol, return_wfn=False)
Both the CI and CC do pick up the freezing of the core doubly occupied orbitals, but not the virtuals. Maybe this is not the right approach?