Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 96: Frontiers of Electronic-Structure Theory: Correlated Electron Materials VII (joint session O/TT/MM/DS/CPP)
TT 96.6: Vortrag
Donnerstag, 15. März 2018, 16:30–16:45, HL 001
Reduced Density Matrix Theory for Coupled Fermion-Boson Systems — •Florian Buchholz1, Iris Theophilou1, Michael Ruggenthaler1, Heiko Appel1, and Angel Rubio1,2,3 — 1MPSD, Hamburg, Germany — 2CCQ, The Flatiron Institute, New York, United Sates — 3Nano-bio Spectroscopy Group, San Sebastián, Spain
Reduced density matrix (RDM) theory proved to be successful in describing a wide range of many-body problems that are not easily accessible by the more common many-body perturbation theories or density functional theory. Especially as RDM theories are non-perturbative, they are advantageous in strong coupling scenarios.
However, RDM theory was to our knowledge never applied to systems with more than one active particle type. The focus of this talk is to analyze the possibilities and problems of an extension to coupled fermion-boson theories. Comparing a typical bilinear interaction term of the form ci+cj(ak++ak), where c+/c and a+/a indicate fermion and boson creation/annihilation operators, respectively and the fermionic 2-body interaction term ci+cj+ckcl, the former should have a considerably reduced definition space, which we hope to be exploitable. On the other hand, the bilinear interaction has a very different structure than the 2-body interaction and it is not clear at all, how to define a RDM that carries all information to compute experimental observables of a coupled fermion-boson system.
Specifically, I will illustrate some of the peculiarities of the fermion-boson interaction for simple model systems and present some ideas to deal with those.