A corresponding states principle for the equation of state of hard body fluid mixtures

A theoretically based corresponding-states principle is developed for ather mal mixtures consisting of hard molecules. The principle states that when s caled appropriately, the excess compressibility factor for such mixtures re duces to a universal function of the effective packing fraction of the mixt ure. The latter represents the number density reduced by means of the effec tive molecular volume, which is defined as the volume a molecule excludes t o any point of another molecule and depends on the geometry of both molecul es. The scaling factor is related to a sort of effective nonsphericity para meter for the mixture that depends on composition as well as the nonspheric ity parameters of the molecules which form the mixture and their effective molecular volumes. The universal function represents the excess compressibi lity factor of a pure hard-sphere fluid. Results are in good agreement with available simulation data. (C) 2001 Elsevier Science B.V. All rights reser ved.