code: @Override
      public DescriptorValue calculate(IBond aBond, IAtomContainer atomContainer) {
          IAtomContainer ac;
          IBond bond;
  
          try {
              ac = (IAtomContainer) atomContainer.clone();
              bond = ac.getBond(atomContainer.indexOf(aBond));
              AtomContainerManipulator.percieveAtomTypesAndConfigureAtoms(ac);
          } catch (CDKException e) {
              return getDummyDescriptorValue(e);
          } catch (CloneNotSupportedException e) {
              return getDummyDescriptorValue(e);
          }
  
          if (maxIterations != -1 && maxIterations != 0) electronegativity.setMaxIterations(maxIterations);
  
          double electroAtom1 = electronegativity.calculateSigmaElectronegativity(ac, bond.getBegin());
          double electroAtom2 = electronegativity.calculateSigmaElectronegativity(ac, bond.getEnd());
  
          return new DescriptorValue(getSpecification(), getParameterNames(), getParameters(), new DoubleResult(
                  Math.abs(electroAtom1 - electroAtom2)), NAMES);
  
      }
docs: The method calculates the sigma electronegativity of a given bond
  It is needed to call the addExplicitHydrogensToSatisfyValency method from the class tools.HydrogenAdder.
  
  @param  atomContainer                AtomContainer
  @return return the sigma electronegativity