Seniority zero transformer

.pylintdict

@@ -406,6 +406,7 @@ scipy
 sd
 sdg
 sdt
+seniorityzerotransformer
 serine
 setia
 setted

qiskit_nature/properties/grouped_property.py

@@ -70,6 +70,22 @@ def add_property(self, prop: Optional[T_co]) -> None:
                 name = prop.__class__.__name__
             self._properties[name] = prop
 
+    def remove_property(self, prop: Union[str, Type[Property]]) -> Optional[T_co]:
+        """Removes a property from the group.
+
+        Args:
+            prop: the name or type of the property to remove from the group.
+
+        Returns:
+            The removed property (or None).
+        """
+        name: str
+        if isinstance(prop, str):
+            name = prop
+        else:
+            name = prop.__name__
+        return self._properties.pop(name, None)
+
     def get_property(self, prop: Union[str, Type[Property]]) -> Optional[T_co]:
         """Gets a property from the group.
 

qiskit_nature/transformers/second_quantization/electronic/__init__.py

@@ -1,6 +1,6 @@
 # This code is part of Qiskit.
 #
-# (C) Copyright IBM 2021.
+# (C) Copyright IBM 2021, 2022.
 #
 # This code is licensed under the Apache License, Version 2.0. You may
 # obtain a copy of this license in the LICENSE.txt file in the root directory
@@ -27,13 +27,16 @@
 
    ActiveSpaceTransformer
    FreezeCoreTransformer
+   SeniorityZeroTransformer
 
 """
 
 from .active_space_transformer import ActiveSpaceTransformer
 from .freeze_core_transformer import FreezeCoreTransformer
+from .seniority_zero_transformer import SeniorityZeroTransformer
 
 __all__ = [
     "ActiveSpaceTransformer",
     "FreezeCoreTransformer",
+    "SeniorityZeroTransformer",
 ]

qiskit_nature/transformers/second_quantization/electronic/active_space_transformer.py

@@ -367,24 +367,13 @@ def _transform_property(self, prop: Property) -> Property:
         if isinstance(prop, GroupedProperty):
             transformed_property = deepcopy(prop)
 
-            # Get the iterator of the Group's properties. We access __iter__() directly to make
-            # mypy happy :-)
-            iterator = transformed_property.__iter__()
-
-            transformed_internal_property = None
-            while True:
-                try:
-                    # Send the transformed internal property to the GroupedProperty generator.
-                    # NOTE: in the first iteration, this variable is None, which is equivalent to
-                    # starting the iterator.
-                    # NOTE: a Generator's send method returns the iterators next value [2].
-                    # [2]: https://docs.python.org/3/reference/expressions.html#generator.send
-                    internal_property = iterator.send(transformed_internal_property)
-                except StopIteration:
-                    break
-
+            for internal_property in iter(prop):
                 try:
                     transformed_internal_property = self._transform_property(internal_property)
+                    if transformed_internal_property is not None:
+                        transformed_property.add_property(transformed_internal_property)
+                    else:
+                        transformed_property.remove_property(internal_property.name)
                 except TypeError:
                     logger.warning(
                         "The Property %s of type %s could not be transformed!",
@@ -393,6 +382,9 @@ def _transform_property(self, prop: Property) -> Property:
                     )
                     continue
 
+            if len(transformed_property._properties) == 0:
+                transformed_property = None
+
         elif isinstance(prop, IntegralProperty):
             # get matrix operator of IntegralProperty
             fock_operator = prop.integral_operator(self._density_inactive)