def heh_system():
    basis = 'sto-3g'
    multiplicity = 1
    charge = 1
    geometry = [('He', [0.0, 0.0, 0.0]), ('H', [0, 0, 0.75])]
    molecule = MolecularData(geometry, basis, multiplicity, charge)
    # Run Psi4.
    molecule = run_psi4(molecule,
                        run_scf=True,
                        run_mp2=False,
                        run_cisd=False,
                        run_ccsd=False,
                        run_fci=True,
                        delete_input=False)

    molecule, gs_wf, n_density, eigen_val = get_molecule_openfermion(molecule, eigen_index=2)
    rdm_generator = SpinOrbitalDensity(n_density, molecule.n_qubits)
    transform = jordan_wigner
    return n_density, rdm_generator, transform, molecule
def system_h4():
    print('Running System Setup H4')
    basis = 'sto-3g'
    multiplicity = 1
    charge = 0
    r = 0.75
    geometry = [('H', [0.0, 0.0, 0.0]), ('H', [0, 0, r]), ('H', [0, 0, 2 * r]),
                ('H', [0, 0, 3 * r])]
    molecule = MolecularData(geometry, basis, multiplicity, charge)
    # Run Psi4.
    molecule = run_psi4(molecule,
                        run_scf=True,
                        run_mp2=False,
                        run_cisd=False,
                        run_ccsd=False,
                        run_fci=True,
                        delete_input=False)

    molecule, gs_wf, n_density, eigen_val = get_molecule_openfermion(
        molecule, eigen_index=0)
    rdm_generator = AntiSymmOrbitalDensity(n_density, molecule.n_qubits)
    transform = jordan_wigner
    return n_density, rdm_generator, transform, molecule