AN IMPROVED OPTICAL-POTENTIAL FOR MANY-ELECTRON GREENS-FUNCTION CALCULATIONS - LIH AND H2O

An analysis of an approximate expression for the optical potential given by its functional derivative formulation, shows which are the diagrams left out at each order. A possible method which attempts to introduce the missing diagrams without losing the advantages provided by the functional derivative approach, is proposed. Numerical results are reported for LiH and H2O.