Some Comments on the Variational Approach to the Theory of Simple Liquids

The recently proposed variational approach to the perturbation theory of liquids is examined. It is found that although the approach yields good results in many applications, the use of the difference between the actual and reference intermolecular potentials as a perturbation can allow the perturbation to be infinite for some intermolecular separations. At best, this is unattractive and, at worst, will lead to poor results.