Low-angle structure factor calculations for a model classical fluid

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Abstract
The authors have calculated the small-k behaviour of the structure factor S(k) of a model fluid whose interatomic potential consists of a hard-sphere repulsive core and Lennard-Jones attractive tail using the random-phase approximation (RPA) and the mean-density approximation (MDA). The attempt to assess these theories in comparison with Monte Carlo (MC) simulation results available in the literature highlighted the unreliability of the MC results in the particular region of S(k) they have studied, which they attribute to shortcomings in the algorithm used to extrapolate the radial distribution function g(r) beyond the range obtained by the computer simulation result. Moreover they argue that any attempt to develop a reliable extrapolation procedure for g(r) is inextricably linked to the availability of a good theory for the small-k behaviour of S(k); such a theory does exist at the moment. Any such theory should, in the light of this work, satisfy-as a necessary though not sufficient condition-the requirements of thermodynamic consistency.