Volume dependence of the Grüneisen γ and other thermodynamic properties of NaCI

The quasi-harmonic approximation is used to calculate the Helmholtz free energy F of NaCl. The interionic forces are represented by a deformation-dipole model, which is parameterized self-consistently. We give a parameterized expression for F which can be used to predict the temperature and volume dependence of the thermodynamic properties. The expression for F is tested by comparing our predicted values for the heat capacity C_p, the thermal expansion α, and the bulk modulus B_s with experimental atmospheric-pressure values and by comparing predicted values for the Grüneisen γ at high pressures with the recent measurements of Boehler, Getting and Kennedy. Excellent agreement is obtained. Predictions for the volume dependence of C_p, α, and B_s and for the isothermal equation of state at room temperature are given. Values for the logarithmic derivative q_T = (?Inγ?? In V)_T and for the Anderson-Grüneisen parameters δ_S and δ_T are also given.