Added axis to AbsorptionSpectrum

src/nomad_simulations/properties/permittivity.py

@@ -66,6 +66,7 @@ def __init__(
         super().__init__(m_def, m_context, **kwargs)
         self.rank = [3, 3]
         self.name = self.m_def.name
+        self._axes_map = ['xx', 'yy', 'zz']
 
     def resolve_type(self) -> str:
         frequencies = get_variables(self.variables, Frequency)
@@ -97,8 +98,11 @@ def extract_absorption_spectra(
         spectra = []
         for i in range(3):
             val = self.value[:, i, i].imag
-            absorption_spectrum = AbsorptionSpectrum(variables=frequencies)
+            absorption_spectrum = AbsorptionSpectrum(
+                axis=self._axes_map[i], variables=frequencies
+            )
             absorption_spectrum.value = val
+            absorption_spectrum.physical_property_ref = self
             spectra.append(absorption_spectrum)
         return spectra
 

src/nomad_simulations/properties/spectral_profile.py

@@ -22,7 +22,7 @@
 import pint
 
 from nomad import config
-from nomad.metainfo import Quantity, SubSection, Section, Context
+from nomad.metainfo import Quantity, SubSection, Section, Context, MEnum
 
 from ..utils import get_sibling_section, get_variables
 from ..physical_property import PhysicalProperty
@@ -525,6 +525,14 @@ class AbsorptionSpectrum(SpectralProfile):
 
     # ! implement `iri` and `rank` as part of `m_def = Section()`
 
+    axis = Quantity(
+        type=MEnum('xx', 'yy', 'zz'),
+        description="""
+        Axis of the absorption spectrum. This is related with the polarization direction, and can be seen as the
+        principal term in the tensor `Permittivity.value` (see permittivity.py module).
+        """,
+    )
+
     def __init__(
         self, m_def: Section = None, m_context: Context = None, **kwargs
     ) -> None:

tests/test_permittivity.py

@@ -121,8 +121,10 @@ def test_extract_absorption_spectra(
         absorption_spectra = permittivity.extract_absorption_spectra(logger)
         if absorption_spectra is not None:
             assert len(absorption_spectra) == 3
-            assert absorption_spectra[0].rank == []
-            assert len(absorption_spectra[0].value) == len(variables[0].points)
-            assert np.allclose(absorption_spectra[0].value, result)
+            spectrum = absorption_spectra[1]
+            assert spectrum.rank == []
+            assert spectrum.axis == 'yy'
+            assert len(spectrum.value) == len(variables[0].points)
+            assert np.allclose(spectrum.value, result)
         else:
             assert absorption_spectra == result