code: public DescriptorValue calculatePlus(IAtomContainer container) throws CDKException {
  
          ArrayList<Double> dar = new ArrayList<Double>();
          for (Iterator<IAtom> itA = container.atoms().iterator(); itA.hasNext();) {
              IAtom atom = itA.next();
              double value = IonizationPotentialTool.predictIP(container, atom);
              if (value != 0) dar.add(value);
          }
          for (Iterator<IBond> itB = container.bonds().iterator(); itB.hasNext();) {
              IBond bond = itB.next();
              if (bond.getOrder() == IBond.Order.DOUBLE & bond.getBegin().getSymbol().equals("C")
                      & bond.getEnd().getSymbol().equals("C")) {
                  double value = IonizationPotentialTool.predictIP(container, bond);
                  if (value != 0) dar.add(value);
  
              }
          }
  
          DoubleArrayResult results = arrangingEnergy(dar);
  
          return new DescriptorValue(getSpecification(), getParameterNames(), getParameters(), results,
                  getDescriptorNames(), null);
  
      }
docs: It calculates the 1,2,.. ionization energies of a molecule.
  
  @param  container         AtomContainer
  @return                   The 1, 2, .. ionization energies
  @exception  CDKException  Possible Exceptions