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PGI-1 Seminar: Dr. Giovanna Lani

Towards a Novel Approach for the Calculation of Many-Body Green's Functions

21.May.2012 11:30

European Theoretical Spetroscopy Facility, Ecole Polytechnique, Palaissau


Nowadays, calculations of quasi-particle band structures and photoemission spectra of materials often rely on perturbative many-body techniques such as the GW approximation. In this approach the one-body Green's function (GF) is accessed from a Dyson equation containing a self-energy kernel which is approximated in a simple way. While generally successful, GW is known to poorly describe strong effects of correlation in solids. In this talk I will discuss an alternative route, non perturbative and self-energy free, for calculating the one-body GF. The idea consists of solving a set of non-linear, differential, functional equations, which are pivotal to many-body perturbation theory.
I will first present the results obtained within a simple model, and then move on to describe progressive generalizations of the approach. I will conclude showing how to analytically calculate a family of solutions for the one-body GF and how to pick the physical one among them, by using a number of specific constraints.


Prof. Dr. Stefan Blügel
Phone: +49 2461 61-4249
Fax: +49 2461 61-2850