CHEMICAL-POTENTIALS OF HARD POLYATOMIC SOLUTES IN HARD-SPHERE FLUIDS

Monte Carlo measurements of the chemical potential of hard polyatomics of different conformations dissolved in hard sphere fluids are report ed. These are compared with analytical expressions derived from the ha rd fluid model, performed as a function of solute size and solvent den sity. An excluded volume approximation, which is exact at low density, is found to compare favorably with simulation results for solutes of low asymmetry. This equates the chemical potential of an arbitrarily s haped hardbody solute with that of a sphere of the same excluded volum e. For solutes of high asymmetry systematic deviations from this exclu ded volume approximation are found. New analytical relations between t he optimal effective hard sphere diameter and solute asymmetry are sug gested. These yield quantitatively accurate chemical potential predict ions for hardbody solutes of arbitrary size and shape, up to liquid de nsities. (C) 1997 American Institute of Physics.