Monte Carlo and reverse Monte Carlo simulations on molten zinc chloride

Abstract

Monte Carlo and reverse Monte Carlo simulations on molten ZnCl₂ were performed on the basis of the total atom pair correlation functions, recently determined with X-ray diffraction experiments at T=623 and 873 K. A new pair-wise additive potential model is presented that is based on an intermediate-range oscillating function for the Zn–Zn interaction in combination with a modified Coulomb potential. This potential mimics the effect of induced anion polarization, which has been found as to be the reason for the highly directional interactions between the cations and anions in the melt. With this simple potential model, the experimentally determined total atom pair correlation functions and the total structure factor, the prepeak included, are well reproduced. The analysis of the configurations, generated with the Monte Carlo method, confirms the existence of a network structure with rings and chains of small and medium size consistent with corner connected [ZnCl₄] units of high tetrahedricity. In contrast, the reverse Monte Carlo method generates more disordered structures and is obviously not able to give a correct description of the ion arrangement in molten ZnCl₂.