Hugenholtz-type diagrams

Here we can construct three different Hugenholtz-type diagrams (Fig. 5)... 

The diagrams just discussed—with antisymmetrized vertices at spin-orbital level — are of Hugenholtz type [32]. One can alternatively define [30] diagrams of Goldstone type [33] with spin-free vertices. 

Fig. 22. Fourth-order skeleton (A) and Hugenholtz skeleton (B) diagrams of double excitation type. By providing arrows in all possible ways, all the fourth-order antisymmetrized and Hugenholtz doubles are restored.

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