Green's function method with energy-independent vertex functions

Tsay Tzeng S.Y. ; Kuo T.T.S. ; Tzeng Y. ; Geyer H.B. ; Navratil P. (1996)


In conventional Green's function methods the vertex function T is generally energy dependent. However, a model-space Green's function method where the vertex function is manifestly energy independent can be formulated using energy-independent effective interaction theories based on folded diagrams and/or similarity transformations. This is discussed in general and then illustrated for a 1p1h model-space Green's function applied to a solvable Lipkin many-fermion model. The poles of the conventional Green's function are obtained by solving a self-consistent Dyson equation and model space calculations may lead to unphysical poles. For the energy-independent model-space Green's function only the physical poles of the model problem are reproduced and are in satisfactory agreement with the exact excitation energies.

Please refer to this item in SUNScholar by using the following persistent URL:
This item appears in the following collections: