SOF-7417: fix non-colin nspins for bandstructure plot

express/properties/non_scalar/two_dimensional_plot/band_structure.py

@@ -16,7 +16,16 @@ class BandStructure(TwoDimensionalPlotProperty):
 
     def __init__(self, name, parser, *args, **kwargs):
         super(BandStructure, self).__init__(name, parser, *args, **kwargs)
-        self.nspins = self.parser.nspins()
+        # there could be three possibilities for nspins:
+        # (1) non-magnetic ==> nspins = 1
+        # (2) collinear magnetic (LSDA) ==> nspins = 2
+        # (3) non-collinear magnetic ==> nspins = 4
+        # Prior to Quantum ESPRESSO version 6.4, the XML output contains tag
+        # NUMBER_OF_SPIN_COMPONENTS, which is set to 4 for non-collinear case,
+        # and we return the same for versions above 6.4 if noncolin is True.
+        # However, for non-collinear magnetic case there are one eigenvalue per
+        # k-pont. Here we override nspins for non-collinear case.
+        self.nspins = self.parser.nspins() if self.parser.nspins() != 4 else 1
 
         self.eigenvalues_at_kpoints = self.parser.eigenvalues_at_kpoints()
         if kwargs.get("remove_non_zero_weight_kpoints", False):