| المستخلص: |
We present theoretical calculations of the direct correlation function [DCF], c(r), structure factor, S(q), and the radial distribution function [RDF], g(r), for liquid C60 at high temperatures up to the liquid-vapor critical point. We employed the sticky hard-sphere (SHS) model, in particular, the Baxter solution of the Percus -Yevick approximation to the Ornstein-Zernike (OZ) equation. The SHS model potential has only one temperature parameter is the sticky parameter, r, that can be obtained via the second virial coefficient, B2(T), which is calculated via C60 pair potential. We also employed the sticky hard-sphere plus Yukawa potential (SHSYK) to incorporate the effect of intermediate-range attractive forces. The simplified random phase approximation [RPA] is used to obtain analytical expressions for c(r). Then we carried out the necessary Fourier transform (FT) of c(r) to obtain analytical expression for c(q) and S(q). Also we carried out the q → 0 limit of S(q) to obtain the isothermal compressibility, kT, via the compressibility equation of state. The screening length, L, of the Yukawa function was obtained by fitting the computed kT with that from the thermodynamic perturbation theory [PT]. Also we carried out numerical inverse Fourier transform (IFT) of S(q) to obtain the radial distribution function, g(r). The results of c(r), S(q) and g(r) for expanded C60 at different temperatures are presented and discussed. In particular, the results of g(r) could explain the nature of expansion mechanism of C60 at extreme conditions of temperatures.
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