Abstract
Based on the Grüneisen assumption, thermodynamic analysis of the Grüneisen equation of state leads us to the introduction of two new thermal variables, the product of which forms the thermal internal energy. One of them, . Θ (v) defines a characteristic temperature of solids as a function of volume, while the other, C (S) is a state variable as a function of entropy, and conjugate to . Θ (v). The specific heat is shown to be a function of entropy. These results are also derived by the statistical mechanics of harmonic oscillator systems, but not using the Debye model.
