Relationship between energy gaps and melting temperatures in various classes of materials

An interesting relationship between the energy gaps and melting temperatures in a variety of classes of materials is found. The relationship suggests the existence of two different processes for the melting phenomenon which depend on the nature of the chemical bond. By using the bond orbital theory, it is shown that the relationship is correlated with the total energy of the compounds considered. A brief discussion on the melting of superionic conductors is also given.