Darmstadt 2008 – scientific programme

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MO: Fachverband Molekülphysik

MO 22: Theorie: Quantenchemie und Moleküldynamik

MO 22.3: Poster

Thursday, March 13, 2008, 16:30–19:00, Poster C1

Exact Wave-Packet Propagation for a Field Coupled Molecular System Employing a Perturbative Expansion — •Ciprian Padurariu¹, Philipp Marquetand², Volker Engel², and Ulrich Kleinekathöfer¹ — ¹Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany — ²Institut für Physikalische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany

A method for solving the time-dependent Schrödinger equation numerically for a field coupled two electronic state system is presented. In each state, wave packets are propagated using the established split-operator technique. However, the transitions between the electronic surfaces are not treated within the standard generalization of this method to the two state problem which involves numerical evaluations of trigonometrical functions at each instant of time. In the proposed approach, the coupling is treated within time-dependent perturbation theory. The method relies on the observation that the perturbation wave function at time t+dt can be obtained directly from the one at time t. A re-summation of the individual orders at each timestep dt is not necessary. Numerical results on a one-dimensional model system prove the robustness of the method, also exhibiting savings of approximately 35% in computation time compared to the standard split-operator technique for two surfaces. This is in particular important for higher dimensional systems where the computational effort is drastically reduced.