Dresden 2020 – scientific programme

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DS: Fachverband Dünne Schichten

DS 23: Frontiers in Electronic-Structure Theory - Focus on Electron-Phonon Interactions III (joint session O/CPP/DS/HL)

DS 23.11: Talk

Wednesday, March 18, 2020, 13:15–13:30, GER 38

Conical intersections in molecular systems: 3D vs 2D models — •Erik Pillon, Dmitry Fedorov, Péter Szabó, and Alexandre Tkatchenko — University of Luxembourg, 1511 Luxembourg

The molecular Aharonov-Bohm effect [1], covering various phenomena caused by the Berry (geometric or topological) phase in molecular systems, is an important playground for understanding fundamental quantum physics as well as for building quantum electronic devices. The related non-adiabatic effects, stemming from the coupling between the electron and nuclear degrees of freedom, are especially pronounced in systems possessing conical intersections (CI) in potential energy surfaces, ubiquitous in condensed matter and molecular physics. Many toy models have been introduced to study the influence of CIs on the nuclear dynamics from a general point of view. However, most of them, including the linear vibronic coupling model [2, 3] widely used in literature, employ two-dimensional (2D) real Hamiltonians. In our work, we check whether such models capture all the important features of real molecular systems. To this end, we perform a comparison of the conventional approaches with the general treatment of a CI within the three-dimensional (3D) complex Hamiltonian possessing SU(2) symmetry [4]. The features present within the 3D model but missing in the 2D case are identified and discussed.

[1] Zygelman, J. Phys. B: At. Mol. Opt. Phys. 50, 025102 (2017)

[2] Longuet-Higgins et al., Proc. R. Soc. A 244, 1 (1958)

[3] Jahn and Teller, Proc. R. Soc. A 161, 220 (1937)

[4] Berry, Proc. R. Soc. A 392, 45 (1984)