Figure 9.
Diagrammatic representation of Equations (13–17). The GW approximation reduces the self-energy to a product of G with W. The first equation (Dyson's equation) has a G line on the left- and right-hand sides. This equation can be iterated, inserting G0 + G0ΣG in place of each G on the RHS, forming the Dyson series. The same iterative procedure for W forms its own Dyson series.