Calculation of isothermal compressibility of potassium halide melts and in binary mixtures KI–KX (X = F, Cl, Br) by the classical molecular dynamics

Calculations of the isothermal compressibility (ᵡ_T) of individual potassium halides and some binary mixtures, namely KI–KX (X = F, Cl, Br), by using the classical molecular dynamics were carried out. Simulations of potassium halide melts using the Born-Mayer-Huggins pair potential showed good agreement between the calculated isothermal compressibility values and experimental data. A systematic underestimation of the calculated ᵡ_T values for individual melts was discovered, with the maximum difference between the calculated and experimental values being 24% for potassium chloride. For binary mixtures KI–KX (X = F, Cl, Br), the experimental concentration dependences of ᵡ_T during the transition from bromide ion to fluoride ion are characterized by an increasing deviation from additivity. It is shown, that even now for the binary mixture KI–KBr, the calculated concentration dependence ᵡ_T has a pronounced nonlinear dependence. At the same time, the maximum differences between the calculated and experimental values of ᵡ_T are observed for the KI–KF binary mixture of equimolar composition and are about 34%.