Perturbation theory for the angular correlation function

A perturbation expression for the angular pair correlation function g (2)(r 12, ω1, ω2) is derived for systems interacting via non central potentials based on the method developed by Gubbins and Gray [1]. The method uses the ‘correct’ (in the sense of Rushbrooke [3] and Cook and Rowlinson [4]) angle-averaged potential as the reference system about which the perturbation is made. A preliminary comparison between the original Gubbins-Gray expression for g (2)(r 12, ω1, ω2) and the present expression is made for a system of two-dimensional point dipoles.