 For decades physicists had been trying to incorporate the effect of microscopic quantum mechanical interactions between electrons in the theory of matter.Bohm and Pines' RPA accounts for the weak screened Coulomb interaction and is commonly used for describing the dynamic linear electronic response of electron systems.In the RPA, electrons are assumed to respond only to the total electric potential "V"(r) which is the sum of the external perturbing potential "V"ext(r) and a screening potential "V"sc(r).