code: def tersoff_potential(self, structure):
          
          bv = BVAnalyzer()
          el = [site.specie.symbol for site in structure]
          valences = bv.get_valences(structure)
          el_val_dict = dict(zip(el, valences))
  
          gin = "species \n"
          qerfstring = "qerfc\n"
  
          for key in el_val_dict.keys():
              if key != "O" and el_val_dict[key] % 1 != 0:
                  raise SystemError("Oxide has mixed valence on metal")
              specie_string = key + " core " + str(el_val_dict[key]) + "\n"
              gin += specie_string
              qerfstring += key + " " + key + " 0.6000 10.0000 \n"
  
          gin += "# noelectrostatics \n Morse \n"
          met_oxi_ters = TersoffPotential().data
          for key in el_val_dict.keys():
              if key != "O":
                  metal = key + "(" + str(int(el_val_dict[key])) + ")"
                  ters_pot_str = met_oxi_ters[metal]
                  gin += ters_pot_str
  
          gin += qerfstring
          return gin
docs: Generate the species, tersoff potential lines for an oxide structure
  
          Args:
              structure: pymatgen.core.structure.Structure