Use reference bands to count num valence

Author: qiaojunfeng

Diff for: src/aiida_wannier90_workflows/workflows/split.py

@@ -396,7 +396,12 @@ def inspect_valcond(self):  # pylint: disable=inconsistent-return-statements
         fermi_energy = get_workchain_fermi_energy(workchain)
         self.ctx.fermi_energy = fermi_energy
 
-        bands: orm.BandsData = workchain.outputs.band_structure
+        # Prioritize reference bands, since Wannier-interpolated bands might have
+        # interpolation error
+        if self.ctx.ref_bands is None:
+            bands: orm.BandsData = workchain.outputs.band_structure
+        else:
+            bands: orm.BandsData = self.ctx.ref_bands
         bands_arr = bands.get_bands()
         try:
             homo, lumo = get_homo_lumo(bands_arr, fermi_energy)