diff --git a/tests/test_atoms_state.py b/tests/test_atoms_state.py
index f251542a..8d20b5b4 100644
--- a/tests/test_atoms_state.py
+++ b/tests/test_atoms_state.py
@@ -116,6 +116,14 @@ def test_degeneracy(
         resolved_degeneracy = orbital_state.resolve_degeneracy()
         assert resolved_degeneracy == degeneracy
 
+    def test_normalize(self, orbital_state):
+        """
+        Test the normalization of the `OrbitalsState`. Inputs are defined as the quantities of the `OrbitalsState` section.
+        """
+        orbital_state.normalize(None, self.logger)
+        # assert orbital_state.degeneracy == 6
+        # assert orbital_state.occupation == 0.0
+
 
 class TestCoreHole:
     """
@@ -173,7 +181,7 @@ def test_normalize(
         self, core_hole, orbital_ref, n_excited_electrons, dscf_state, results
     ):
         """
-        Test the normalization of the `CoreHole` state. Inputs are defined as the quantities of the `CoreHole` section.
+        Test the normalization of the `CoreHole`. Inputs are defined as the quantities of the `CoreHole` section.
         """
         core_hole.orbital_ref = orbital_ref
         core_hole.n_excited_electrons = n_excited_electrons
@@ -261,3 +269,16 @@ def test_u_effective(
             assert np.isclose(resolved_u_effective.to("eV").magnitude, u_effective)
         else:
             assert resolved_u_effective == u_effective
+
+    def test_normalize(self, hubbard_interactions):
+        """
+        Test the normalization of the `HubbardInteractions`. Inputs are defined as the quantities of the `HubbardInteractions` section.
+        """
+        hubbard_interactions.u_interaction = 3.0 * ureg("eV")
+        hubbard_interactions.u_interorbital_interaction = 1.0 * ureg("eV")
+        hubbard_interactions.j_hunds_coupling = 3.0 * ureg("eV")
+
+        hubbard_interactions.normalize(None, self.logger)
+        assert hubbard_interactions.u_effective == 2.0 * ureg("eV")
+        assert hubbard_interactions.u_interaction == 3.0 * ureg("eV")
+        assert hubbard_interactions.j_local_exchange_interaction == 1.0 * ureg("eV")
diff --git a/tests/test_model_system.py b/tests/test_model_system.py
new file mode 100644
index 00000000..01698458
--- /dev/null
+++ b/tests/test_model_system.py
@@ -0,0 +1,31 @@
+#
+# Copyright The NOMAD Authors.
+#
+# This file is part of NOMAD. See https://nomad-lab.eu for further info.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+import pytest
+
+from simulationdataschema.model_system import AtomicCell
+
+
+class TestAtomicCell:
+    @pytest.fixture(autouse=True)
+    def atomic_cell(self):
+        return AtomicCell(
+            lattice_vectors=[[1, 0, 0], [0, 1, 0], [0, 0, 1]],
+            positions=[[0, 0, 0], [0.5, 0.5, 0.5]],
+            species=["H", "O"],
+        )