code: def potcar_symbols(self):
          
          elements = self.poscar.site_symbols
          potcar_symbols = []
          settings = self._config_dict["POTCAR"]
  
          if isinstance(settings[elements[-1]], dict):
              for el in elements:
                  potcar_symbols.append(settings[el]['symbol']
                                        if el in settings else el)
          else:
              for el in elements:
                  potcar_symbols.append(settings.get(el, el))
  
          return potcar_symbols
docs: List of POTCAR symbols.