diff --git a/tangelo/problem_decomposition/dmet/dmet_problem_decomposition.py b/tangelo/problem_decomposition/dmet/dmet_problem_decomposition.py
index 0d2d2f33a..e9b211cd1 100644
--- a/tangelo/problem_decomposition/dmet/dmet_problem_decomposition.py
+++ b/tangelo/problem_decomposition/dmet/dmet_problem_decomposition.py
@@ -176,6 +176,9 @@ def __init__(self, opt_dict):
         self.orb_list2 = None
         self.onerdm_low = None
 
+        # If save_results in _oneshot_loop is True, the dict is populated.
+        self.solver_fragment_dict = dict()
+
     @property
     def quantum_fragments_data(self):
         """This aims to return a dictionary with all necessary components to
diff --git a/tangelo/toolboxes/ansatz_generator/qcc.py b/tangelo/toolboxes/ansatz_generator/qcc.py
index 179f85443..4e5605a65 100644
--- a/tangelo/toolboxes/ansatz_generator/qcc.py
+++ b/tangelo/toolboxes/ansatz_generator/qcc.py
@@ -40,7 +40,6 @@
 from tangelo.toolboxes.qubit_mappings.mapping_transform import get_qubit_number,\
                                                                fermion_to_qubit_mapping
 from tangelo.linq import Circuit
-from tangelo import SecondQuantizedMolecule
 from tangelo.toolboxes.ansatz_generator.ansatz import Ansatz
 from tangelo.toolboxes.ansatz_generator.ansatz_utils import exp_pauliword_to_gates
 from tangelo.toolboxes.ansatz_generator._qubit_mf import init_qmf_from_hf, get_qmf_circuit, purify_qmf_state
@@ -55,9 +54,11 @@ class QCC(Ansatz):
     state is obtained using a RHF or ROHF Hamiltonian, respectively.
 
     Args:
-        molecule (SecondQuantizedMolecule or dict): The molecular system, which can
-            be passed as a SecondQuantizedMolecule or a dictionary with keys that
-            specify n_spinoribtals, n_electrons, and spin. Default, None.
+        molecule (SecondQuantizedMolecule, SecondQuantizedDMETFragment or dict):
+            The molecular system, which can be passed as a
+            SecondQuantizedMolecule/SecondQuantizedDMETFragment or a dictionary
+            with keys that specify n_spinoribtals, n_electrons, and spin.
+            Default, None.
         mapping (str): One of the supported qubit mapping identifiers. Default, "jw".
         up_then_down (bool): Change basis ordering putting all spin-up orbitals first,
             followed by all spin-down. Default, False.
@@ -86,18 +87,20 @@ def __init__(self, molecule, mapping="jw", up_then_down=False, dis=None,
                  qmf_circuit=None, qmf_var_params=None, qubit_ham=None, qcc_tau_guess=1e-2,
                  deqcc_dtau_thresh=1e-3, max_qcc_gens=None, reference_state="HF"):
 
-        if not molecule and not (isinstance(molecule, SecondQuantizedMolecule) and isinstance(molecule, dict)):
-            raise ValueError("An instance of SecondQuantizedMolecule or a dict is required for "
-                             "initializing the self.__class__.__name__ ansatz class.")
+        if isinstance(molecule, dict) and not qubit_ham:
+            raise ValueError(f"An instance of SecondQuantizedMolecule or a dict"
+                " + qubit operator is required for initializing the "
+                f"{self.__class__.__name__} ansatz class.")
+
         self.molecule = molecule
-        if isinstance(self.molecule, SecondQuantizedMolecule):
-            self.n_spinorbitals = self.molecule.n_active_sos
-            self.n_electrons = self.molecule.n_active_electrons
-            self.spin = self.molecule.spin
-        elif isinstance(self.molecule, dict):
+        if isinstance(self.molecule, dict):
             self.n_spinorbitals = self.molecule["n_spinorbitals"]
             self.n_electrons = self.molecule["n_electrons"]
             self.spin = self.molecule["spin"]
+        else:
+            self.n_spinorbitals = self.molecule.n_active_sos
+            self.n_electrons = self.molecule.n_active_electrons
+            self.spin = self.molecule.spin
 
         self.mapping = mapping
         self.up_then_down = up_then_down