Estimation of ion-induced dipole interactions to the thermodynamics of alkali halide melts

The statistical-thermodynamic model to account for the ion-induced dipole interactions in molten alkali halides through thermodynamic perturbation theory is proposed. The main contribution to the free energy of these melts was described on the basis of charged hard spheres model as the reference system. The expression for the charge-induced dipole term to the free energy in Fourier space was also presented. Estimations and analysis of the extra contribution to the thermodynamic characteristics of alkali halide melts were carried out. The perturbation due to the induced dipoles is confirmed to be negative for all alkali halides, while the reduced value of the extra term lies in the range from a few to 10% for free energy. The absolute values of the ion-induced dipole term are greater in those melts where the basic Coulomb interaction is also greater. Generally, the proposed model is quantitatively successful when describing the enthalpy and its temperature dependence without fitting parameters. [Display omitted] •Perturbation theory is developed to account for ion-dipole effects in halide melts.•Charge-induced dipole contribution to thermodynamics was estimated without fitting.•The enthalpies over alkali halides show good agreement with the experimental data.