On the Debye temperature and Gruneisen parameters for hexagonal close-packed crystals consisting of p-H2 and o-D2 molecules

The expressions for the Debye temperature I similar to as well as for the first (gamma = -[a,ln(I similar to)/a,ln(V)] (T) ) and second (q = [a,ln(gamma)/a,ln(V)] (T) ) Gruneisen parameters are derived based on the Mie-Lennard-Jones pair atomic interaction potential. The conditions imposed on the I similar to(V/V (0)), gamma(V/V (0)), and q(V/V (0)) dependences for V/V (0) -> 0 and for V/V (0) -> a are analyzed. Here, V/V (0) is the ratio of the molar volumes for pressure P at temperature T and for P = 0 at T = 0 K. Calculations are performed for crystals of parahydrogen and orthodeuterium at T = 0 K for V/V (0) ranging from 1.30 to 0.01. Good agreement is reached between the calculated dependences and experimental data. The behavior of dependences I similar to(V/V (0)), gamma(V/V (0)), and q(V/V (0)) upon a variation of the isotopic composition of the crystal is analyzed.