A simple pseudomolecular fluid model. Exact and approximate structural properties

A simple model mimicking a molecular fluid is introduced, whose properties can be calculated easily and essentially exactly. A range of properties, including the spherical harmonic expansion coefficients, both of the pair correlation function and of the background correlation function, are calculated. The model is a useful tool to assess the accuracy of molecular fluid theories, and we demonstrate this use by considering two approaches currently available. It is also demonstrated that the model can be used to estimate the properties of realistic molecular fluid models.