The Debye temperatures of hexagonal crystals of 42 elements and compounds have been calculated from the elastic constants, by numerical integration and by Pynn's method. It is found that Pynn's method is inapplicable in certain cases; the cause of this is analyzed, and a modification of Pynn's method is suggested for these cases. The calculated Debye temperatures are compared with the calorimetric Debye temperatures, wherever data are available. Large discrepancies are pointed out for Pr, Dy, Ho, and Er, and small ones for Be, Mg, Y, Ti, Zr, Hf, and Tb.

• Received 24 February 1981

DOI:https://doi.org/10.1103/PhysRevB.24.4340