Making the Fermi level a scalar to avoid problems.

HISTORY.rst

@@ -1,6 +1,12 @@
 =======
 History
 =======
+2023.11.8 -- Bugfix: Fermi level being an array caused problems
+    * The Fermi level in DFTB+ is a vector with 1 or 2 elements, depending whether the
+      calculation is spin-polarized. DFTB+ can handle different Fermi levels, but it is
+      not clear how useful this is, so for the time being not allowing such calculations
+      and treating the Fermi level as a scalar.
+
 2023.11.7 -- Added structure to orbital and density plots
     * The Dashboard expects 'structure.sdf' in order to display the structure with the
       orbital or debsity plots from CUBE files.

dftbplus_step/base.py

@@ -616,7 +616,12 @@ def parse_results(self, lines):
                     if _type == "real":
                         values = [float(x) for x in values]
 
-                    property_data[key] = redimension(values, dims)
+                    if key == "fermi_level":
+                        # The Fermi level has one or two values if spin-polarized, but
+                        # normally they are the same, so turn into a scalar.
+                        property_data[key] = values[0]
+                    else:
+                        property_data[key] = redimension(values, dims)
                 if key not in properties:
                     self.logger.warning("Property '{}' not recognized.".format(key))
                 if key in properties and "units" in properties[key]:

dftbplus_step/energy.py

@@ -618,7 +618,8 @@ def analyze(self, indent="", data={}, out=[]):
 
         # Prepare the DOS graph(s)
         if "fermi_level" in data:
-            Efermi = list(Q_(data["fermi_level"], "hartree").to("eV").magnitude)
+            # Efermi = list(Q_(data["fermi_level"], "hartree").to("eV").magnitude)
+            Efermi = [Q_(data["fermi_level"], "hartree").to("eV").magnitude]
         else:
             Efermi = [0.0]
         wd = Path(self.directory)

dftbplus_step/metadata.py

@@ -46,7 +46,7 @@
             "optimization",
         ],
         "description": "The Fermi level",
-        "dimensionality": [2],
+        "dimensionality": "scalar",
         "property": "Fermi level#DFTB+#{model}",
         "type": "float",
         "units": "E_h",