Anomalous propagators and the particle-particle channel of correlation

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• Antoine Marie, Universite Paul Sabatier
• Monday 15 July 2024, 14:00-15:00
• Yusuf Hamied Department of Chemistry, Pfizer Lecture Theatre; Zoom link: https://zoom.us/j/92447982065?pwd=RkhaYkM5VTZPZ3pYSHptUXlRSkppQT09.

If you have a question about this talk, please contact Alexander R Epstein.

Hedin’s equations provide an elegant route to compute the exact one-body Green’s function (or propagator) via the self-consistent iteration of a set of non-linear equations. Its first-order approximation, known as GW, corresponds to a resummation of ring diagrams and has shown to be extremely successful in physics and chemistry. Systematic improvement is possible, although challenging, via the introduction of vertex corrections. Considering anomalous propagators and an external pairing potential, we derive a new self-consistent set of closed equations equivalent to the famous Hedin equations but having as a first-order approximation the particle-particle (pp) T-matrix approximation where one performs a resummation of the ladder diagrams (known as the pp random phase approximation (RPA)). This pp version of Hedin’s equations offers a way to go systematically beyond the $T$-matrix approximation by accounting for low-order pp vertex corrections. In particular, we will show how to go beyond the pp-RPA-based T-matrix by formulating the Bethe-Salpeter equation for the two-particle propagator and discussing some of its approximations.

This talk is part of the Lennard-Jones Centre series.

This talk is included in these lists:

• Hanchen DaDaDash
• Lennard-Jones Centre
• Yusuf Hamied Department of Chemistry, Pfizer Lecture Theatre; Zoom link: https://zoom.us/j/92447982065?pwd=RkhaYkM5VTZPZ3pYSHptUXlRSkppQT09

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