code: def hubbards(self):
          
          symbols = [s.split()[1] for s in self.potcar_symbols]
          symbols = [re.split(r"_", s)[0] for s in symbols]
          if not self.incar.get("LDAU", False):
              return {}
          us = self.incar.get("LDAUU", self.parameters.get("LDAUU"))
          js = self.incar.get("LDAUJ", self.parameters.get("LDAUJ"))
          if len(js) != len(us):
              js = [0] * len(us)
          if len(us) == len(symbols):
              return {symbols[i]: us[i] - js[i] for i in range(len(symbols))}
          elif sum(us) == 0 and sum(js) == 0:
              return {}
          else:
              raise VaspParserError("Length of U value parameters and atomic "
                                    "symbols are mismatched")
docs: Hubbard U values used if a vasprun is a GGA+U run. {} otherwise.