Gru¨neisen γ and other thermodynamic properties of cesium halide crystals at zero and elevated pressures

The quasiharmonic approximation is used to calculate the Helmholtz free energy F. The interionic forces are represented by a deformation‐dipole model, which is parameterized self‐consistently. We give parameterized expressions for F that can be used to predict the temperature and volume dependence of the thermodynamic properties of CsCl, CsBr, and CsI. These expressions for F are tested by comparing our predicted values for the heat capacity CP and the thermal expansion α with experimental atmospheric‐pressure values. Good agreement is obtained. Predicted values for CV, α, BT, the compression −ΔV/V0, and the Gru¨neisen γ at elevated pressures are given, as are zero‐pressure values for the logarithmic derivative qT= (∂lnγ/∂lnV)T and the Anderson‐Gru¨neisen parameters δS and δT.