Update legend in eFNV plots as discussed with @adair-nicolson

doped/corrections.py

@@ -42,6 +42,7 @@
 from monty.json import MontyDecoder
 from pymatgen.analysis.defects.corrections import freysoldt
 from pymatgen.analysis.defects.utils import CorrectionResult
+from pymatgen.core.periodic_table import Element
 from pymatgen.io.vasp.outputs import Locpot, Outcar
 from shakenbreak.plotting import _install_custom_font
 
@@ -472,6 +473,11 @@ def get_kumagai_correction(
             )
             for label in labels
         ]
+        dummy_h = Element("H")  # dummy element to check if valid symbol
+        labels = [
+            label + r" ($V_{defect} - V_{bulk}$)" if dummy_h.is_valid_symbol(label) else label
+            for label in labels
+        ]
 
         # add entry for dashed red line:
         handles += [Line2D([0], [0], **spp._mpl_defaults.hline)]