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HK: Fachverband Physik der Hadronen und Kerne
HK 70: Structure and Dynamics of Nuclei XII
HK 70.3: Talk
Thursday, March 31, 2022, 16:45–17:00, HK-H6
Excited states from eigenvector continuation: the anharmonic oscillator — •Margarida Companys Franzke1, Alexander Tichai1,2,3, Kai Hebeler1,2,3, and Achim Schwenk1,2,3 — 1Technische Universität Darmstadt, Department of Physics — 2ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH — 3Max-Plank Institut für Kernphysik, Heidelberg
Eigenvector continuation (EC) has recently attracted a lot attention in nuclear structure and reactions as a variational resummation tool for many-body expansions. While previous applications focused on ground-state energies, excited states can be accessed on equal footing. This work is dedicated to a detailed understanding of the emergence of excited states from the eigenvector continuation approach. For numerical applications the one-dimensional quartic anharmonic oscillator is investigated, which represents a strongly non-perturbative quantum system where the use of standard perturbation techniques break down. We discuss how different choices for the construction of the EC manifold affect the quality of the EC resummation and investigate in detail the results from EC for excited states compared to results from a full diagonalization as a function of the basis-space size.
* Funded by the DFG -- Project-ID 279384907 -- SFB 1245 and by the ERC Grant Agreement No. 101020842.