APPLICATION OF THE LENNARD-JONES (N, M) POTENTIAL FUNCTION TO QUANTUMCRYSTALS IN THE SELF-CONSISTENT PHONON THEORY

The Lennard-Jones (n, m) potential energy parameters for quantum cryst als whose structure are b.c.c. and h.c.p. are calculated. The potentia l parameters are fitted to experimental data of the sublimation energy , zero point volume and zero point compressibility. The obtained resul ts are in turn used to calculate the pressure variations of the dynami cal and thermodynamical functions of the crystal lattices of He-3 and He-4 in the reduced second-order self-consistent phonon theory. The re sults show reasonable agreement with experimental data.