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A theoretical study of the thermodynamic properties in the Einstein-Debye approximation is made for solids with polyatomic basis. Analytical expressions are derived for the equation of state, isobaric specific heat ( C p ) , and linear thermal expansion coefficient ( a p ) . The temperature dependences of Cp and a p are determined by four characteristic parameters of the solid: the Debye temperature 190, the Einstein temperature BE, and the Griineisen parameters y g and 7 : associated with the volume dependences of 00 and BE, respectively. It is shown that the difference Cp -Cv between the calculated isobaric and isochoric specific heat capacities is very sniall at low temperatures (T << OD) and increases markedly at higher temperatures. In the high-tempcraturc range (T >> &), Cp is almost independent of temperature and is determined by a simple combination of the Griineisen parameters y g and y:. The results obtained for a p , in the low-arid high-temperature limits, are in accord with thosc found for the asymptotic behavior of with temperature.

A theoretical study in the Debye approximation is made of the isobaric specific heat (C,) and thermal expansion of solids with a Bravais lattice. Analytical expressions are obtained for the variations of Cp and the linear thermal expansion coefficient (ap) with temperature. The temperature dependence of C p is determined by two characteristic parameters of the solid: the Debye temperature 0 and the Gruneisen parameter yc. It is shown that the difference C p -Cv between the calculated isobaric and isochoric specific heat capacities is very small at low temperatures (T < 0) and increases markedly at higher temperatures. In the range T B 0, C p is almost independent of temperature and is.determined solely by yG. This provides a technique to estimate the Gruneisen parameter yG from the measurements of isobaric specific heat at high temperatures. The results obtained for ap, in the low-and high-temperature limits, are in agreement with those in literature.