A simple quasiharmonic model, employing a valence-force approach, is used to calculate the Grüneisen functions and thermal expansion of tellurium. The calculations illustrate the use of a new thermodynamic formalism for treating internal strain and reveal explicitly the effect that an internal degree of freedom has upon the macroscopic properties. The valenceforce picture of tellurium is critically discussed in the light of a comparison of the calculations with experiment. Suggestions are made for further experimental work and for improvements in the theoretical model.

• Received 2 June 1972

DOI:https://doi.org/10.1103/PhysRevB.7.1410