Square well potential. IV. Use of a modification of the Kirkwood superposition approximation

Abstract

The Yvon-Born-Green integral equation with the Kirkwood superposition approximation is modified via a truncation of dense fluid contribution to third-particle correlations at the boundary of the intermolecular potential wells of the interacting molecular pair. This de-emphasis of third-body contributions, manifesting itself in a ``truncated superposition approximation,'' improves a broad spectrum of equilibrium and transport property predictions significantly while simultaneously shortening the computational extent of the integral equation problem. The results are compared with earlier work performed by the authors using the Kirkwood superposition approximation and with experiment. The nature of both the Kirkwood and truncated superposition approximations is discussed in light of recent schemes used to shorten the computations required to obtain solutions to the Percus-Yevick integral equation.