The concept of the thermal potential, introduced in earlier publications in connection with calculations of elastic properties, thermal expansion, and melting temperatures, is shown to be a unifying principle connecting the thermodynamic properties of the solid and molten states. Recently discovered extrapolations connecting the thermodynamic properties of the solid and molten states are demonstrated to be governed by the characteristics of the thermal potential. A simple model of the melting entropy is presented and combined with previously derived expressions involving parameters of the thermal potential to quantitatively connect the heat of fusion with the volume change at melting. The melting entropy is calculated for a group of cubic crystals with the use of the derived expressions, and good agreement is found with observed values. A principal conclusion of this work is that the shear modulus, heat content, and volume, which are discontinuous at the melting temperature, are continuous functions of each other and related through the parameters of the thermal potential.

• Received 3 December 1981

DOI:https://doi.org/10.1103/PhysRevB.25.5895