New method for the calculation of the pair correlation function. I

A new method is described to approximate the pair correlation function. A discussion is given of the structure of the Mayer type of diagrams which correspond to the different contributions to the pair correlation function. The method takes into account in the successive steps of the approximation, diagrams of increasing complexity as regards “ the basic structure”, a concept which is fully defined in this paper in §5. In each step of the approximation an infinity of diagrams, corresponding to density terms up to infinite order, is included. Numerical calculations are in progress for evaluating the pair correlation function in the “zeroth” approximation, which takes into account all diagrams, which can be obtained by successive series and parallel connection of subdiagrams, using the single bond as starting element. It is possible that also the next step in the approximation, including diagrams of a more complex basic structure, can be made with high speed computors.