Berlin 2014 – scientific programme
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MO: Fachverband Molekülphysik
MO 9: Theory 2: Molecular Dynamics & Quantum Chemistry
MO 9.8: Talk
Tuesday, March 18, 2014, 15:45–16:00, BEBEL SR144
Exact factorization of the electron-nuclear wave function: Is the molecular Berry phase an artefact of the Born-Oppenheimer approximation? — •Seung Kyu Min1,2, Ali Abedi1, Kwang S. Kim2, and E.K.U. Gross1 — 1Max-Planck-Institut für Mikrostrukturphysik Weinberg 2, D-06120 Halle, Germany — 2Pohang University of Science and Technology, Korea
The Born-Oppenheimer (BO) potential energy surfaces (PESs) provide an intuitive picture to analyze and interpret molecular processes. In this context, conical intersections (CIs) of the BO PESs are particularly important. They provide pathways for radiationless relaxation processes within the BO framework. Berry phases may arise when the Hamiltonian of a system depends on a set of parameters. In the BO approximation, the electronic Hamiltonian depends parametrically on the nuclear positions. If the full wave function (WF) is approximated by a single product of an electronic BO WF and a single nuclear WF, the varational equation determining the latter contains a Berry-type vector potential. However, in experiment, CIs and the associated Berry phases do not appear directly. One wonders whether the specific topological feature of Berry phase is an artifact of the BO approximation or whether it can be found for the exact full WF as well. To adress this question we employ the exact factorization of the full WF which leads to a rigorous definition of the Berry connection [1,2]. Using a numerical study of a simple model, we answer the question whether the appearance of CIs and Berry phases survives in the exact treatment.[1]arXiv cond-mat/0502433 [2]PRL 105,123002 (2005)