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TT: Fachverband Tiefe Temperaturen
TT 65: Focused Session: Frontiers of Electronic Structure Theory 7 (jointly with HL and O)
TT 65.6: Vortrag
Donnerstag, 14. März 2013, 17:15–17:30, H36
Initial stages of time-evolution of excitations in Fermi liquids and finite systems — •Yaroslav Pavlyukh1, Jamal Berakdar1, and Angel Rubio2 — 1Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle, Germany — 2Nano-Bio Spectroscopy Group and ETSF Scientific Development Centre, Dpto. de Física de Materiales, Universidad del País Vasco, CFM CSIC-UPV/EHU-MPC and DIPC, Av. Tolosa 72, E-20018 San Sebastián, Spain
A particle-hole excitation in a many-body system is not an eigenstate and, thus, evolves in time. The evolution at short times after an excitation with the energy є was created is the quadratic decay with the rate constant σ2(є). Later, after some set-in time τ(є), the exponential decay develops. It is governed by another rate constant γ(є).
We study the electron-boson model for the homogenous electron gas and use the first order (in boson propagator) cumulant expansion of the electron Green’s function. In addition to a quadratic decay in time upon triggering the excitation, we identify non-analytic terms in the time expansion similar to those found in the Fermi edge singularity phenomenon.
Finite systems (J. Chem. Phys., 135, 201103 (2011)) give an opportunity to test the conjectured behavior numerically as an exact solution of a many-body problem is feasible. We propose a simple model for the electron spectral function that links together all three aforementioned parameters and give a prescription how the energy uncertainty σ2(є) can be computed within the many-body perturbation theory.