diff --git a/src/nomad_parser_vasp/parsers/xml_parser.py b/src/nomad_parser_vasp/parsers/xml_parser.py
index 8d48092..2905376 100644
--- a/src/nomad_parser_vasp/parsers/xml_parser.py
+++ b/src/nomad_parser_vasp/parsers/xml_parser.py
@@ -3,6 +3,7 @@
 from nomad.datamodel.datamodel import EntryArchive
 from nomad.parsing import MatchingParser
 from nomad.parsing.file_parser.xml_parser import XMLParser
+from nomad.units import ureg
 from nomad_simulations.general import Program, Simulation
 from nomad_simulations.model_method import DFT, XCFunctional
 from nomad_simulations.model_system import AtomicCell, ModelSystem
@@ -12,6 +13,7 @@
 from nomad_parser_vasp.schema_packages.vasp_schema import (
     HartreeDCEnergy,
     TotalEnergy,
+    UnknownEnergy,
     XCdcEnergy,
 )
 
@@ -87,14 +89,19 @@ def xml_get(path: str, slicer=slice(0, 1), fallback=None):
             )
 
         total_energy = xml_get("i[@name='e_fr_energy']", slice(-2, -1))
+        total_energy = total_energy[0] if total_energy else None
         hartreedc = xml_get("i[@name='hartreedc']", slice(-2, -1))
+        hartreedc = hartreedc[0] if hartreedc else None
         xcdc = xml_get("i[@name='XCdc']", slice(-2, -1))
+        xcdc = xcdc[0] if xcdc else None
 
         output = Outputs()
-        archive.simulation.outputs.append(output)
+        archive.data.outputs.append(output)
         output.total_energy.append(TotalEnergy(value=total_energy * ureg.eV))
 
         output.total_energy[0].contributions.append(
             HartreeDCEnergy(value=hartreedc * ureg.eV)
         )
         output.total_energy[0].contributions.append(XCdcEnergy(value=xcdc * ureg.eV))
+
+        output.total_energy[0].contributions.append(UnknownEnergy(value=None))
diff --git a/src/nomad_parser_vasp/schema_packages/vasp_schema.py b/src/nomad_parser_vasp/schema_packages/vasp_schema.py
index 8ad8609..9ddd497 100644
--- a/src/nomad_parser_vasp/schema_packages/vasp_schema.py
+++ b/src/nomad_parser_vasp/schema_packages/vasp_schema.py
@@ -16,16 +16,34 @@ def normalize(self, archive: 'EntryArchive', logger: 'BoundLogger') -> None:
 
 
 class HartreeDCEnergy(DoubleCountingEnergy):
+    def __init__(
+        self, m_def: 'Section' = None, m_context: 'Context' = None, **kwargs
+    ) -> None:
+        super().__init__(m_def, m_context, **kwargs)
+        self.name = self.m_def.name
+
     def normalize(self, archive: 'EntryArchive', logger: 'BoundLogger') -> None:
         super().normalize(archive, logger)
 
 
 class XCdcEnergy(DoubleCountingEnergy):
+    def __init__(
+        self, m_def: 'Section' = None, m_context: 'Context' = None, **kwargs
+    ) -> None:
+        super().__init__(m_def, m_context, **kwargs)
+        self.name = self.m_def.name
+
     def normalize(self, archive: 'EntryArchive', logger: 'BoundLogger') -> None:
         super().normalize(archive, logger)
 
 
 class UnknownEnergy(EnergyContribution):
+    def __init__(
+        self, m_def: 'Section' = None, m_context: 'Context' = None, **kwargs
+    ) -> None:
+        super().__init__(m_def, m_context, **kwargs)
+        self.name = self.m_def.name
+
     def normalize(self, archive: 'EntryArchive', logger: 'BoundLogger') -> None:
         super().normalize(archive, logger)
 
@@ -40,13 +58,15 @@ def normalize(self, archive: 'EntryArchive', logger: 'BoundLogger') -> None:
             return
 
         value = self.value
-        unknown_energy_exists = False
-        for contribution in self.contributions:
+        i_unknown = None
+        for i_cont, contribution in enumerate(self.contributions):
+            if contribution.name == 'UnknownEnergy':
+                i_unknown = i_cont
+
             if not contribution.value:
                 continue
-            if contribution.name == 'UnknownEnergy':
-                unknown_energy_exists = True
 
             value -= contribution.value
-        if not unknown_energy_exists:
-            self.contributions.append(UnknownEnergy(value=value))
+
+        if i_unknown:
+            self.contributions[i_unknown].value = value