An effective method for hard sphere diameters of real fluids along the coexistence line vapour-liquid

The variation of the effective hard sphere diameter with the temperature along the equilibrium line vapour-liquid has been analyzed for a great variety of substances including: (a) atomic simple liquids; (b) inorganic and organic molecular liquids and (c) liquid metals, following several procedures, based in the analogy with a hard sphere fluid. Though the comparison among available methods is generally satisfactory, the method based on internal pressure seems to be more effective.