Hannover 2013 – scientific programme

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MO: Fachverband Molekülphysik

MO 27: Poster 3: Collisions, Electronic Spectroscopy, Energy Transfer, Quantum Chemistry, Molecular Dynamics, Photochemistry, Spectroscopy in He-Droplets

MO 27.1: Poster

Thursday, March 21, 2013, 16:00–18:30, Empore Lichthof

Non-linear Spectra from Equilibrium Trajectories — •Tobias Zentel, Sergei D. Ivanov, and Oliver Kühn — Universität Rostock, Wismarsche Str. 43-45, Germany

Non-linear spectroscopic methods are an useful tool to investigate dynamics of molecular systems. The signals can be formulated in terms of response functions, which consist of dipole correlation functions. These can be calculated in the classical limit via an equilibrium trajectory approach [1]. The key element to calculate classical response functions are stability matrices, a measure for how chaotic a system is. The stability matrices stay finite and oscillate for quasi-periodic systems, but diverge exponentially in time for chaotic systems. The non-linear classical response functions in quasi-periodic systems always diverge along one or more time direction, even so the stability matrices stay bound [2]. In chaotic systems, on the other hand, it is possible to compute response functions up to a point where the stability matrix computation becomes unstable, which is due to the exponentially divergence of its elements. However by thermal averaging a reasonable response function can still be computed. In the present contribution this issue is studied for a Henon-Heiles model systems and results compared to quantum mechanical calculations. Furthermore different integrators for the stability matrix propagation are tested and it is analyzed how this influences the classical response functions.

[1] J. Jeon, M.Cho, New J. Phys.12, 6 (2012); [2] M. Kryvohuz, J. Cao Phys. Rev. Lett. 96, 3 (2006)