Calculation of the isothermal compressibility of molten potassium halides by the molecular dynamics method is carried out. It is shown that as the radii differences between the anions of the constituent binary mixture increase, the interparticle interactions in the system increase. This is manifested in a greater deviation from the additivity of the isothermal compressibility of the KCl-KI mixture as compared to the KBr-KI mixture
