MONTE-CARLO AND INTEGRAL-EQUATION STUDIES OF HARD-OBLATE-SPHEROCYLINDER FLUIDS

Hard-oblate spherocylinders with reduced core diameters l = l/sigma = 1, 2, 3 are studied at several packing fractions up to eta = 0.45. Mo nte Carlo results are given for the first six spherical harmonic coeff icients of the pair distribution function, g(klm)(r), and for the comp ressibility factors. These results are compared with the hypernetted c hain (HNC), Percus-Yevick (PY), and modified Verlet (VM) approximation s. The VM theory produces very good results for the g000 harmonic coef ficient at low and medium densities and for the reduced coefficients g (klm) = g(klm)/g000 at all densities considered. The PY and HNC resul ts are less accurate and none of the theories satisfactorily describes the 9000 harmonic coefficient at eta = 0.45. The VM theory gives equa tion-of-state results in excellent agreement with the simulation data, whereas the PY values of the compressibility factors at medium and hi gh densities are too low while the HNC values are too high. The thermo dynamic consistency between the pressure and the compressibility equat ions is also tested for each of the PY, HNC, and VM theories. At all s tate points considered the consistency of the VM theory is much better than that of the PY and HNC theories. Finally, we report results for the first bridge diagram (the first term in the density expansion of t he bridge function) at several specific orientations of the root molec ules.