Materials can be described as a derivation of existing "parent" materials in order to alter few of their features, such as density. CompareMaterial compare materials taking into account their possible "affiliation"
G4DNAMolecularMaterial builds tables of molecular densities for chosen molecular materials. The class handles homogeneous, composite and derived materials. A material of interest is labeled as molecular if built using the number of atoms rather than the mass fractions
1.8.7 
