diff --git a/simulationdataschema/atoms_state.py b/simulationdataschema/atoms_state.py
index d62de417..5584f913 100644
--- a/simulationdataschema/atoms_state.py
+++ b/simulationdataschema/atoms_state.py
@@ -178,7 +178,7 @@ def __init__(self, m_def: Section = None, m_context: Context = None, **kwargs):
             'ms_numbers': dict((zip(('down', 'up'), (-0.5, 0.5)))),
         }
 
-    def _quantum_numbers_check(self, logger: BoundLogger) -> bool:
+    def _check_quantum_numbers(self, logger: BoundLogger) -> bool:
         """
         Checks the physicality of the quantum numbers.
 
@@ -191,10 +191,10 @@ def _quantum_numbers_check(self, logger: BoundLogger) -> bool:
         if self.n_quantum_number < 1:
             logger.error('The `n_quantum_number` must be greater than 0.')
             return False
-        if self.l_quantum_number and self.l_quantum_number < 1:
+        if self.l_quantum_number is not None and self.l_quantum_number < 1:
             logger.error('The `l_quantum_number` must be greater than 0.')
             return False
-        if self.ml_quantum_number and (
+        if self.ml_quantum_number is not None and (
             self.ml_quantum_number < -self.l_quantum_number
             or self.ml_quantum_number > self.l_quantum_number
         ):
@@ -202,7 +202,10 @@ def _quantum_numbers_check(self, logger: BoundLogger) -> bool:
                 'The `ml_quantum_number` must be between `-l_quantum_number` and `l_quantum_number`.'
             )
             return False
-        if self.ms_quantum_number and self.ms_quantum_number not in [-0.5, 0.5]:
+        if self.ms_quantum_number is not None and self.ms_quantum_number not in [
+            -0.5,
+            0.5,
+        ]:
             logger.error('The `ms_quantum_number` must be -0.5 or 0.5.')
             return False
         return True
@@ -311,7 +314,7 @@ def normalize(self, archive, logger) -> None:
         super().normalize(archive, logger)
 
         # General checks for physical quantum numbers and symbols
-        if not self._quantum_numbers_check(logger):
+        if not self._check_quantum_numbers(logger):
             logger.error('The quantum numbers are not physical.')
             return
 
diff --git a/tests/test_atoms_state.py b/tests/test_atoms_state.py
index 383dcfe3..f037e3e7 100644
--- a/tests/test_atoms_state.py
+++ b/tests/test_atoms_state.py
@@ -59,6 +59,27 @@ def add_state(
     def orbital_state(self) -> OrbitalsState:
         return OrbitalsState(n_quantum_number=2)
 
+    @pytest.mark.parametrize(
+        'number, values, results',
+        [
+            ('n_quantum_number', [-1, 0, 1, 2], [False, False, True, True]),
+            ('l_quantum_number', [-2, 0, 1, 2], [False, False, True, True]),
+            # l_quantum_number == 2 when testing 'ml_quantum_number'
+            ('ml_quantum_number', [-3, 5, -2, 1], [False, False, True, True]),
+            ('ms_quantum_number', [0, 10, -0.5, 0.5], [False, False, True, True]),
+        ],
+    )
+    def test_check_quantum_numbers(self, orbital_state, number, values, results):
+        """
+        Test the quantum number check for the `OrbitalsState` section.
+        """
+        for val, res in zip(values, results):
+            if number == 'ml_quantum_number':
+                orbital_state.l_quantum_number = 2
+            setattr(orbital_state, number, val)
+            check = orbital_state._check_quantum_numbers(self.logger)
+            assert check == res
+
     @pytest.mark.parametrize(
         'quantum_name, quantum_type, value, countertype, expected_result',
         [