flowchart TD id1(No central field!) id2(Shell model) id3(Hartree-Fock) id4(HF-BCS) id5(HF-Bogoliuvob) id6(QRPA) id7(Brückner-HF) id1-->|Average phenomenological potential|id2 id1-->|Self consistent field from a 2-particle potential|id3 id3-->|"Add pairing (pp) correlations"|id4 id4-->|Generalize pairing/HF with quasiparticles|id5 id5-->|"Add long distance (ph) correlations"|id6 id3-->|Density dependent forces|id7 id7-.->id4